Add a cosmetic message for when the install ref is already resolved.
Fix the template name in the message logged when that name is ambiguous.
Merge pull request #261 from 99designs/for_ben/xcode_tools

Xcode tools not being available should not proceed
Don't define @@tmp_prefix at the top level when running specs, silencing a ruby-2.0 warning.
Fail fast on non-directory entries in ~/.babushka/sources -- it's less surprising that way.
v0.16.2 - Fix 'xcode tools' met? test (thanks @rich0H), stricter ~/.babushka/sources handling, some logging cleanups.
Merge remote-tracking branch 'upstream/master'