Added img for a 'stale remote-tracking branch'
A 'stale remote-tracking branch is one that's been deleted on the
remote repo, yet still is held as a ref in the local repo.
Remote parse could fail when no explicit HEAD exists
During a 'git remote show' parse, if no explicit HEAD branch exists,
the parser would incorrectly NOT advance to the next line,
causing remote branches to NOT be parsed.
improved RemoteBranch UX with icons and tooltips;
Added 'stale', 'new' icons and tooltips for remote branches.