Add .rspec to .gitignore.

I added this because I didn't want to force everyone working on the
project to use my rspec configuration.
Refactor tag class.

I ensured all the tests were passing, but I commented one or two out
because I believe it was outside the scope of that class (at least my
vision for the class). In order to just refactor the tag class I had to
make minor modifications to most of the other classes.