Add exceptions to DRAC plugin
Add exceptions to DRAC plugin

This patch adds exceptions when the DRAC plugin fails, because the supplemental pack is not installed or because the connection or credentials fail.

Signed-off-by: Javier Alvarez-Valle <cf4c8668a0b4c5e013f594a6940d05b3d4d9ddcf@citrix.com>

ravippandey/xen-api,anoobs/xen-api,huizh/xen-api,srowe/xen-api,robertbreker/xen-api,thomassa/xen-api,simonjbeaumont/xen-api,rafalmiel/xen-api,rafalmiel/xen-api,salvocambria/xen-api,simonjbeaumont/xen-api,djs55/xen-api,cheng-z/xen-api,srowe/xen-api,euanh/xen-api,robertbreker/xen-api,agimofcarmen/xen-api,cheng-z/xen-api,huizh/xen-api,ravippandey/xen-api,koushikcgit/xen-api,jjd27/xen-api,guard163/xen-api,koushikcgit/xen-api,djs55/xen-api,Frezzle/xen-api,jjd27/xen-api,salvocambria/xen-api,salvocambria/xen-api,simonjbeaumont/xen-api,simonjbeaumont/xen-api,cheng--zhang/xen-api,vasilenkomike/xen-api,thomassa/xen-api,robertbreker/xen-api,robertbreker/xen-api,anoobs/xen-api,guard163/xen-api,salvocambria/xen-api,ravippandey/xen-api,simonjbeaumont/xen-api,euanh/xen-api,cheng-z/xen-api,srowe/xen-api,anoobs/xen-api,koushikcgit/xen-api,Frezzle/xen-api,jjd27/xen-api,cheng-z/xen-api,vasilenkomike/xen-api,vasilenkomike/xen-api,guard163/xen-api,cheng--zhang/xen-api,anoobs/xen-api,guard163/xen-api,Frezzle/xen-api,djs55/xen-api,thomassa/xen-api,cheng--zhang/xen-api,thomassa/xen-api,ravippandey/xen-api,cheng--zhang/xen-api,ravippandey/xen-api,agimofcarmen/xen-api,jjd27/xen-api,huizh/xen-api,agimofcarmen/xen-api,euanh/xen-api,cheng-z/xen-api,thomassa/xen-api,thomassa/xen-api,agimofcarmen/xen-api,salvocambria/xen-api,djs55/xen-api,huizh/xen-api,koushikcgit/xen-api,guard163/xen-api,rafalmiel/xen-api,simonjbeaumont/xen-api,rafalmiel/xen-api,cheng-z/xen-api,jjd27/xen-api,agimofcarmen/xen-api,cheng-z/xen-api,euanh/xen-api,djs55/xen-api,ravippandey/xen-api,huizh/xen-api,vasilenkomike/xen-api,djs55/xen-api,anoobs/xen-api,cheng--zhang/xen-api,vasilenkomike/xen-api,anoobs/xen-api,euanh/xen-api,jjd27/xen-api,vasilenkomike/xen-api,rafalmiel/xen-api,cheng--zhang/xen-api,guard163/xen-api,salvocambria/xen-api,Frezzle/xen-api,huizh/xen-api,robertbreker/xen-api,cheng--zhang/xen-api,koushikcgit/xen-api,rafalmiel/xen-api,agimofcarmen/xen-api,Frezzle/xen-api,srowe/xen-api,euanh/xen-api,srowe/xen-api,robertbreker/xen-api,koushikcgit/xen-api