Give new users a free account.
Updated .gitignore to include coverage files anywhere in the directory tree.
Create free account type if it doesn't exist; fix tests.
Remove "if account_type" checks in Account.

 - remove account_type_string method
 - simplify paid_until_string.
Use ActiveRecord methods for not_staff join code.

 - set member.account_type directly in tests, because changes to
   member.account.account_type weren't being persisted.
Rake task to give everyone free accounts; fix descriptions.