Throw more user-friendly exception on pack version which doesn't follow valid semver format.
Throw more user-friendly exception on pack version which doesn't follow valid
semver format.

Plexxi/st2,StackStorm/st2,lakshmi-kannan/st2,tonybaloney/st2,nzlosh/st2,StackStorm/st2,peak6/st2,lakshmi-kannan/st2,tonybaloney/st2,nzlosh/st2,Plexxi/st2,peak6/st2,tonybaloney/st2,StackStorm/st2,Plexxi/st2,StackStorm/st2,peak6/st2,nzlosh/st2,lakshmi-kannan/st2,Plexxi/st2,nzlosh/st2