Fix panic on deleting the AppRole which doesn't exist
Fix panic on deleting the AppRole which doesn't exist

#pathRoleDelete should return silently if the specified  AppRole doesn't exist
Fixes GH-1919

rnaveiras/vault,wjam/vault,hashicorp/vault,hashicorp/vault,michaelansel/vault,kingland/vault,danielsomerfield/vault,martin-ducar-gd/vault,hartsock/vault,hartsock/vault,doodles526/vault,hashicorp/vault,jmhardison/vault,quixoten/vault,rnaveiras/vault,kingland/vault,hashicorp/vault,deverton/hashicorp-vault,doodles526/vault,ryon/vault,quixoten/vault,mymercurialsky/vault,naunga/vault,joelthompson/vault,rnaveiras/vault,rnaveiras/vault,Banno/vault,kingland/vault,naunga/vault,jgcallero/vault,lirao/vault,hashicorp/vault,michaelansel/vault,kingland/vault,jam-pot/vault,Aloomaio/vault,Banno/vault,LolalyLuo/vault,cimarron-pistoncloud/vault,mgk/vault,MonsantoCo/vault,chrishoffman/vault,Caiyeon/vault,ryon/vault,Aloomaio/vault,lemondrank/vault,quixoten/vault,hartsock/vault,chrishoffman/vault,jgcallero/vault,quixoten/vault,tallpauley/vault,jmhardison/vault,wjam/vault,mgk/vault,joelthompson/vault,jmhardison/vault,lemondrank/vault,joelthompson/vault,Caiyeon/vault,Aloomaio/vault,cimarron-pistoncloud/vault,mgk/vault,hartsock/vault,jam-pot/vault,joelthompson/vault,Aloomaio/vault,rnaveiras/vault,jmhardison/vault,kingland/vault,hartsock/vault,tallpauley/vault,mgk/vault,LolalyLuo/vault,hashicorp/vault,deverton/hashicorp-vault,lirao/vault,jmhardison/vault,mymercurialsky/vault,MonsantoCo/vault,danielsomerfield/vault,martin-ducar-gd/vault