Runner param can be defined immutable in action
Runner param can be defined immutable in action

* A runner param can be declared immutable in action. In this case,
we can use the 'default' value supplied in either runner or action.
We need default to be specified in at least one place.

lakshmi-kannan/st2,pinterb/st2,peak6/st2,dennybaa/st2,alfasin/st2,armab/st2,pixelrebel/st2,nzlosh/st2,pinterb/st2,alfasin/st2,tonybaloney/st2,nzlosh/st2,grengojbo/st2,StackStorm/st2,Plexxi/st2,jtopjian/st2,Itxaka/st2,Itxaka/st2,tonybaloney/st2,dennybaa/st2,armab/st2,StackStorm/st2,peak6/st2,Plexxi/st2,jtopjian/st2,lakshmi-kannan/st2,peak6/st2,Plexxi/st2,grengojbo/st2,pinterb/st2,Plexxi/st2,alfasin/st2,dennybaa/st2,armab/st2,nzlosh/st2,punalpatel/st2,pixelrebel/st2,tonybaloney/st2,StackStorm/st2,punalpatel/st2,lakshmi-kannan/st2,Itxaka/st2,pixelrebel/st2,nzlosh/st2,emedvedev/st2,emedvedev/st2,StackStorm/st2,emedvedev/st2,jtopjian/st2,punalpatel/st2,grengojbo/st2