membership defined with M2M thorugh model, fixes #28 too
rsvp view working
changed membership model name
resolved pylint issues
Merge pull request #29 from agiliq/rsvp

Rsvp added, bug fixed and views changed to class-based views
added exception for .ds_store in gitignore
rsvp working with event detail view
rsvp delete feature added
unique column issue removed, one test removed, resolved pylint issues