Remove ActiveSupport Dependency

Whereas:
- ActiveSupport has a big footprint.
- Requiring it can affect compatibility with other libraries
- The parts of it used in rbp are minimal

Remove ActiveSupport in favor of custom monkey-patches.
Adding the Inflecto gem as a dependency as it was extracted from
the ActiveSupport Inflector and alows rbp to nicely handle
pluralizing and singularizing strings.
Merge pull request #176 from bf4/remove_activesupport

[#175]  Remove ActiveSupport Dependency