Only show border on actions buttons
Only show border on actions buttons

@rande Like you asked in https://github.com/sonata-project/SonataAdminBundle/pull/2834#issuecomment-82388376

**Normal**
![button-after](https://cloud.githubusercontent.com/assets/663607/6705810/9237bcd6-cd58-11e4-920f-2fb879774c49.JPG)

**Hovered**
![button-hover](https://cloud.githubusercontent.com/assets/663607/6705811/923c20d2-cd58-11e4-9316-b095a0394366.JPG)

I didn't use the btn-outline class for 2 reasons : 
- it's already used in AdminLte with different behavior
- it avoid to add a specific class on these buttons
edouardkombo/SonataAdminBundle,Romashka/SonataAdminBundle,ejkun/SonataAdminBundle,lutangar/SonataAdminBundle,jlamur/SonataAdminBundle,UnDeleteRU/SonataAdminBundle,core23/SonataAdminBundle,ryanhughes/SonataAdminBundle,gnorby88/SonataAdminBundle,rmzamora/SonataAdminBundle,rswork/SonataAdminBundle,claudusd/SonataAdminBundle,greg0ire/SonataAdminBundle,qsomazzi/SonataAdminBundle,Koc/SonataAdminBundle,OskarStark/SonataAdminBundle,goldbroker/SonataAdminBundle,morfin60/SonataAdminBundle,ju1ius/SonataAdminBundle,binhle410/SonataAdminBundle,lutangar/SonataAdminBundle,dmarkowicz/SonataAdminBundle,ryanhughes/SonataAdminBundle,ossinkine/SonataAdminBundle,ruscon/SonataAdminBundle,news-life-media/SonataAdminBundle,j-ledoux/SonataAdminBundle,ARTACK/SonataAdminBundle,vincenttouzet/SonataAdminBundle,FabienD/SonataAdminBundle,Denniskevin/SonataAdminBundle,tunne/SonataAdminBundle,ksom/SonataAdminBundle,tskorupka/SonataAdminBundle,tim96/SonataAdminBundle,jszmidt/SonataAdminBundle,robhunt3r/SonataAdminBundle,Romashka/SonataAdminBundle,robhunt3r/SonataAdminBundle,arbislimen/SonataAdminBundle,arbislimen/SonataAdminBundle,0mars/SonataAdminBundle,osavchenko/SonataAdminBundle,tim96/SonataAdminBundle,sonata-project/SonataAdminBundle,FabienD/SonataAdminBundle,jlamur/SonataAdminBundle,idchlife/SonataAdminBundle,robhunt3r/SonataAdminBundle,tim96/SonataAdminBundle,morfin60/SonataAdminBundle,j-ledoux/SonataAdminBundle,rschumacher/SonataAdminBundle,amine2z/SonataAdminBundle,peter-gribanov/SonataAdminBundle,andythorne/SonataAdminBundle,ruscon/SonataAdminBundle,morfin60/SonataAdminBundle,nexylan/SonataAdminBundle,dankempster/SonataAdminBundle,greg0ire/SonataAdminBundle,gnorby88/SonataAdminBundle,edouardkombo/SonataAdminBundle,Romashka/SonataAdminBundle,Denniskevin/SonataAdminBundle,Th3Mouk/SonataAdminBundle,nexylan/SonataAdminBundle,dmarkowicz/SonataAdminBundle,morgangiraud/SonataAdminBundle,digitalkaoz/SonataAdminBundle,mgdigital/SonataAdminBundle,FabienD/SonataAdminBundle,lutangar/SonataAdminBundle,goldbroker/SonataAdminBundle,nexylan/SonataAdminBundle,ju1ius/SonataAdminBundle,Denniskevin/SonataAdminBundle,ksom/SonataAdminBundle,dankempster/SonataAdminBundle,vincenttouzet/SonataAdminBundle,dmarkowicz/SonataAdminBundle,tunne/SonataAdminBundle,binhle410/SonataAdminBundle,Storke/SonataAdminBundle,Romashka/SonataAdminBundle,Armstrong1992/SonataAdminBundle,jszmidt/SonataAdminBundle,morfin60/SonataAdminBundle,tskorupka/SonataAdminBundle,rmzamora/SonataAdminBundle,fosvn/SonataAdminBundle,ARTACK/SonataAdminBundle,ossinkine/SonataAdminBundle,cmacetko/SonataAdminBundle,fosvn/SonataAdminBundle,mgdigital/SonataAdminBundle,amine2z/SonataAdminBundle,amine2z/SonataAdminBundle,peter-gribanov/SonataAdminBundle,mweimerskirch/SonataAdminBundle,joshlopes/SonataAdminBundle,morgangiraud/SonataAdminBundle,dankempster/SonataAdminBundle,tunne/SonataAdminBundle,Soullivaneuh/SonataAdminBundle,jakublech/SonataAdminBundle,digitalkaoz/SonataAdminBundle,UnDeleteRU/SonataAdminBundle,ejkun/SonataAdminBundle,jordisala1991/SonataAdminBundle,peter-gribanov/SonataAdminBundle,ellementA/SonataAdminBundle,tim96/SonataAdminBundle,OskarStark/SonataAdminBundle,jordisala1991/SonataAdminBundle,rschumacher/SonataAdminBundle,mohebifar/SonataAdminBundle,jszmidt/SonataAdminBundle,claudusd/SonataAdminBundle,jakublech/SonataAdminBundle,osavchenko/SonataAdminBundle,news-life-media/SonataAdminBundle,osavchenko/SonataAdminBundle,fosvn/SonataAdminBundle,qsomazzi/SonataAdminBundle,ju1ius/SonataAdminBundle,qsomazzi/SonataAdminBundle,idchlife/SonataAdminBundle,Soullivaneuh/SonataAdminBundle,j-ledoux/SonataAdminBundle,jakublech/SonataAdminBundle,dmarkowicz/SonataAdminBundle,ruscon/SonataAdminBundle,OskarStark/SonataAdminBundle,digitalkaoz/SonataAdminBundle,cmacetko/SonataAdminBundle,Storke/SonataAdminBundle,ksom/SonataAdminBundle,gRoussac/SonataAdminBundle,gnorby88/SonataAdminBundle,OskarStark/SonataAdminBundle,rschumacher/SonataAdminBundle,cmacetko/SonataAdminBundle,lutangar/SonataAdminBundle,rswork/SonataAdminBundle,lightglitch/SonataAdminBundle,Th3Mouk/SonataAdminBundle,andythorne/SonataAdminBundle,news-life-media/SonataAdminBundle,ellementA/SonataAdminBundle,j-ledoux/SonataAdminBundle,core23/SonataAdminBundle,cmacetko/SonataAdminBundle,Denniskevin/SonataAdminBundle,UnDeleteRU/SonataAdminBundle,mohebifar/SonataAdminBundle,mikemeier/SonataAdminBundle,tunne/SonataAdminBundle,Koc/SonataAdminBundle,tskorupka/SonataAdminBundle,ARTACK/SonataAdminBundle,0mars/SonataAdminBundle,rswork/SonataAdminBundle,binhle410/SonataAdminBundle,core23/SonataAdminBundle,joshlopes/SonataAdminBundle,ejkun/SonataAdminBundle,mohebifar/SonataAdminBundle,mikemeier/SonataAdminBundle,gRoussac/SonataAdminBundle,Armstrong1992/SonataAdminBundle,osavchenko/SonataAdminBundle,nexylan/SonataAdminBundle,rmzamora/SonataAdminBundle,ossinkine/SonataAdminBundle,jordisala1991/SonataAdminBundle,Soullivaneuh/SonataAdminBundle,Koc/SonataAdminBundle,fosvn/SonataAdminBundle,core23/SonataAdminBundle,mgdigital/SonataAdminBundle,ARTACK/SonataAdminBundle,rschumacher/SonataAdminBundle,binhle410/SonataAdminBundle,mgdigital/SonataAdminBundle,greg0ire/SonataAdminBundle,ksom/SonataAdminBundle,osavchenko/SonataAdminBundle,tskorupka/SonataAdminBundle,Th3Mouk/SonataAdminBundle,ejkun/SonataAdminBundle,morgangiraud/SonataAdminBundle,jlamur/SonataAdminBundle,news-life-media/SonataAdminBundle,claudusd/SonataAdminBundle,UnDeleteRU/SonataAdminBundle,binhle410/SonataAdminBundle,sonata-project/SonataAdminBundle,amine2z/SonataAdminBundle,gRoussac/SonataAdminBundle,news-life-media/SonataAdminBundle,jlamur/SonataAdminBundle,claudusd/SonataAdminBundle,digitalkaoz/SonataAdminBundle,idchlife/SonataAdminBundle,joshlopes/SonataAdminBundle,ju1ius/SonataAdminBundle,jordisala1991/SonataAdminBundle,Storke/SonataAdminBundle,vincenttouzet/SonataAdminBundle,edouardkombo/SonataAdminBundle,rmzamora/SonataAdminBundle,mikemeier/SonataAdminBundle,robhunt3r/SonataAdminBundle,ellementA/SonataAdminBundle,joshlopes/SonataAdminBundle,UnDeleteRU/SonataAdminBundle,dankempster/SonataAdminBundle,edouardkombo/SonataAdminBundle,vincenttouzet/SonataAdminBundle,lightglitch/SonataAdminBundle,gRoussac/SonataAdminBundle,arbislimen/SonataAdminBundle,morfin60/SonataAdminBundle,Romashka/SonataAdminBundle,gnorby88/SonataAdminBundle,arbislimen/SonataAdminBundle,lightglitch/SonataAdminBundle,ossinkine/SonataAdminBundle,mweimerskirch/SonataAdminBundle,peter-gribanov/SonataAdminBundle,idchlife/SonataAdminBundle,ruscon/SonataAdminBundle,goldbroker/SonataAdminBundle,rswork/SonataAdminBundle,qsomazzi/SonataAdminBundle,jszmidt/SonataAdminBundle,Storke/SonataAdminBundle,jlamur/SonataAdminBundle,Th3Mouk/SonataAdminBundle,ellementA/SonataAdminBundle,goldbroker/SonataAdminBundle,morgangiraud/SonataAdminBundle,ryanhughes/SonataAdminBundle,0mars/SonataAdminBundle,Soullivaneuh/SonataAdminBundle,FabienD/SonataAdminBundle,mohebifar/SonataAdminBundle,ryanhughes/SonataAdminBundle,lightglitch/SonataAdminBundle,0mars/SonataAdminBundle,greg0ire/SonataAdminBundle,Koc/SonataAdminBundle,mweimerskirch/SonataAdminBundle,dmarkowicz/SonataAdminBundle,andythorne/SonataAdminBundle,andythorne/SonataAdminBundle,mikemeier/SonataAdminBundle,ellementA/SonataAdminBundle,jakublech/SonataAdminBundle,ejkun/SonataAdminBundle,j-ledoux/SonataAdminBundle,mweimerskirch/SonataAdminBundle