`zvm ls --all` doesn't sort versions correctly

[itsrainingmani]

When using zvm ls --all, the currently displayed order is not sorted according to semver. This is likely due to a requirement in semver.Sort that semantic version strings must begin with a leading "v", as in "v1.0.0".

Current Order -

master
0.1.1
0.10.0
0.10.1
0.11.0
0.2.0
0.3.0
0.4.0
0.5.0
0.6.0
0.7.0
0.7.1
0.8.0
0.8.1
0.9.0
0.9.1

Expected Order -

master
0.11.0
0.10.1
0.10.0
0.9.1
0.9.0
0.8.1
0.8.0
0.7.1
0.7.0
0.6.0
0.5.0
0.4.0
0.3.0
0.2.0
0.1.1

[itsrainingmani]

Unrelated to zvm ls --all but I didn't want to make a separate issue for this -

I was poking into the behavior of zvm ls and I noticed that the highlighting of the current version doesn't work if the current version is master. It seems like that case was being handled in an earlier version of ls.go but then got removed. Is there a reason for that?

I'm happy to amend my PR to fix that if that's ok with you :)