fixes broke specs and adds a few new ones.
work around for difference in ruby 1.8/1.9 exceptions -

I'm not sure if this is the best way to handle this since we want Ruby 1.9 to throw a more specific exception (e.g. Gmail::Client::AuthorizationError)
Update depcrecated RSpec syntax.

DEPRECATION: `expect { }.not_to raise_error(SpecificErrorClass)` is
deprecated. Use `expect { }.not_to raise_error` (with no args) instead.
Lock mail dependency to v2.5.3 to fix bug in 1.8.7.

Mail 2.5.4 caused the following error when using 1.8.7:
Gmail::Client::DeliveryError: Couldn't deliver email: wrong argument
(NilClass)! (Expected kind of OpenSSL::SSL::SSLContext).
Merge branch 'fix_specs' into develop
Fix imap extensions in ruby 1.9.3

These constants are defined in Net::IMAP::ResponseParser and
if you don't put the full path to them here it won't work
on ruby 1.9.3