Moved transaction schema definitions into ``_schema``
Version bump
Various improvements

* Working on cleaning up our unicode act (See Issue #1)
* Some cleanup- and documentation work in ``utils``
* Created a ``_schema`` skeleton in ``membership``
Small fixes and improvements

* test_new_order now verifies field values and types
* Moved some method calls out of related methods and into ``__init__``
* Got started specifying Membership API schemas
* Improved some data validation functions