Changed how I handle hrefs to sub-objects not yet fetched.

And local storage for same. Got rid of the `cache` subfield for
accounts and just put subscriptions etc as fields directly on the
object to use if you know you've fetched them. Subobject hrefs are now
in foo._resources hash.

All unit tests pass.
Transactions can now be created & refunded.

With some unit tests.
Add some documentation for newly-implemented transaction functions.
Whitespace changes in the .js file.
Bump version to 0.0.2 to prep for release.
Merge pull request #1 from ceejbot/0.0.2

version 0.0.2: support for transactions