Move Client functions into a class called Session
Subclasses inherit from Voipfone::Session
Remove monkey-patching files, and move functions into new class called Voipfone::Account
Some tidying of constants; added a new configuration option to cache cookies, set some default config options
Cache cookies to save having to log in for every request from a subclass. Hooray. I have removed the option to stop caching because it seems silly
Remove TODO
Bumped version to 0.3.0 because this is a big refactor
Tidy up global divert comments; add class method for clearing diverts
A big readme update for 0.3.0