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.
Xcode tools not being available should not proceed
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.
babushka -> matryoshka
babushka -> matryoshka in files
babushka -> matryoshka in file names