Flag to require the current directory if it's a rails app.

Instead of always trying to require the current directory, provide a
flag so that users can disable loading the current directory. For
instance a rake task in a rails app to load a specific consumer not all
consumers.

closes #35
Merge pull request #36 from coreypurcell/master

Add a flag to turn off loading of the current directory if it's a rails app.
Bump version to v0.3.0