[#175]  Remove ActiveSupport Dependency

See #175


    
    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.
    
    Rbp will fallback on its custom patches if ActiveSupport is not
    available