Add better error messages for IdentityExpectation

The whole "check" thing needs another look at - error messages really
should be able to be created dynamically, each expectation hardly needs
to set its own error every time. That's a lot of code repetition.
Add a file globber class, some specs

Also setup app.php to use the cool new globber
Simplify spec naming in FileGlobberSpec
Refactor FileGlobber, add some (not many) comments
Prepare 0.1.1 release

This adds the FileGlobber support and reduces the number of failures in
HHVM to a mere unidentified and weirdly reproducible core dump.