Added ability for sage specific user-agent
Added ability for sage specific user-agent

Added the ability for sage to set a default user-agent string of "SageTV/x.x.x" for file downloads.  Will only set the new string when property "use_sagetv_user_agent" is set to true, otherwise it will remain the default "Java/x.x.x_xx".
OpenSageTV/sagetv,JustFred51/sagetv,jason-bean/sagetv,enternoescape/sagetv,troll5501/sagetv,rflitcroft/sagetv,jrmull/sagetv,troll5501/sagetv,Slugger/sagetv,jusjoken/sagetv,ai7/sagetv,jreicheneker/sagetv,jfthibert/sagetv,stuckless/sagetv,jfthibert/sagetv,jlverhagen/sagetv,jason-bean/sagetv,ai7/sagetv,JREkiwi/sagetv,skiingwiz/sagetv,BartokW/sagetv,OpenSageTV/sagetv,ckewinjones/sagetv,jusjoken/sagetv,troll5501/sagetv,jrmull/sagetv,jrmull/sagetv,skiingwiz/sagetv,atarijeff/sagetv,enternoescape/sagetv,gasinger/sagetv,gilleslabelle/sagetv,webernissle/sagetv,jusjoken/sagetv,andyvshr/sagetv,JustFred51/sagetv,ai7/sagetv,jreicheneker/sagetv,shyamalschandra/sagetv,OpenSageTV/sagetv,JasOXIII/sagetv,peterSVS/sagetv,troll5501/sagetv,atarijeff/sagetv,andyvshr/sagetv,JREkiwi/sagetv,JREkiwi/sagetv,JasOXIII/sagetv,gasinger/sagetv,ckewinjones/sagetv,jason-bean/sagetv,webernissle/sagetv,Slugger/sagetv,gilleslabelle/sagetv,gilleslabelle/sagetv,stuckless/sagetv,google/sagetv,google/sagetv,JasOXIII/sagetv,gasinger/sagetv,rflitcroft/sagetv,google/sagetv,atarijeff/sagetv,coppit/sagetv,atarijeff/sagetv,BartokW/sagetv,richard-nellist/sagetv,tmiranda1962/sagetv-1,andyvshr/sagetv,JasOXIII/sagetv,stuckless/sagetv,tmiranda1962/sagetv-1,google/sagetv,jlverhagen/sagetv,tmiranda1962/sagetv-1,Slugger/sagetv,ckewinjones/sagetv,jlverhagen/sagetv,webernissle/sagetv,richard-nellist/sagetv,stuckless/sagetv,skiingwiz/sagetv,jrmull/sagetv,BartokW/sagetv,skiingwiz/sagetv,JustFred51/sagetv,BartokW/sagetv,jlverhagen/sagetv,enternoescape/sagetv,neurocis/sagetv,webernissle/sagetv,JREkiwi/sagetv,ckewinjones/sagetv,enternoescape/sagetv,coppit/sagetv,neurocis/sagetv,coppit/sagetv,jfthibert/sagetv,rflitcroft/sagetv,peterSVS/sagetv,shyamalschandra/sagetv,richard-nellist/sagetv,Slugger/sagetv,coppit/sagetv,shyamalschandra/sagetv,tmiranda1962/sagetv-1,neurocis/sagetv,gilleslabelle/sagetv,jason-bean/sagetv,jreicheneker/sagetv,OpenSageTV/sagetv,jfthibert/sagetv,shyamalschandra/sagetv,andyvshr/sagetv,peterSVS/sagetv,ai7/sagetv,richard-nellist/sagetv,neurocis/sagetv,peterSVS/sagetv,jusjoken/sagetv,jreicheneker/sagetv,rflitcroft/sagetv,JustFred51/sagetv,gasinger/sagetv