Update version to 1.5 to prepare release.
Update version to 1.5 to prepare release.

frakc/DraggablePanel,pedrovgs/DraggablePanel,SPBTV/DraggablePanel,hmit/DraggablePanel,murat8505/DraggablePanel,Fiddl3/DraggablePanel,dfodor/DraggablePanel,FreeDao/DraggablePanel,qiwx2012/DraggablePanel,Thornith/DraggablePanel,ppamorim/DraggablePanel,hoangsondev/DraggablePanel