Returns a list of available factories

Adds ability to retrieve a list of factories available in *home*.
This is particularly useful when the client developer does not have access to
*home*'s source code and can not search for available factories for themselves
(i.e. a mobile application developer perhaps).
Merge pull request #1 from tdouce/travisdouce/return_list_of_avialable_factories

Returns a list of available factories