Change structure of returned hash when printing filters for a controller

Previously an array containing all before filters used by an actions in a
controller was printed. The structure has now been changed to organize these
filters by action, e.g.

{
  :new => [:filter1, :filter2],
  :index => [:filter3]
}

API has changed as well. Removed the "show_" portion of the method names for
returning filters for self and all descendants.
Updating README to reflect API changes
Updating gemspec with more information and pointers to documentation
v1.0.0

This is the starting point. API behavior officially decided on.