Added Default customer account logic.

  Paysimple has a class for default customer account, but it
  nothing; so, we are simply going to use customer account in its place.
  Also, added more custom exceptions.
Merge branch 'master' of github.com:/CTA/PS into experiment

Conflicts:
	lib/ps/response.rb
Setting up default customerAccount
Changed how states are called
Merge branch 'master' of github.com:/CTA/PS into experiment

Conflicts:
	lib/ps/exceptions.rb
	lib/ps/response.rb
Begin Implementation of Factory Girl for testing.

Add to Gemfile
Add to specs
Merge branch 'master' of github.com:CTA/PS into kcollette
Implement factories, add tests, implement fixes

Add new factories.
Add new tests.
Implement bug fixes via working with tests.