Pymamba

* Adding addressbook demo (nested relationships)
* A number of related bugfixes

* Complete restructure to allow for application level transactions (for replication)
* Privatised some methods that don't need to be exposed
* Database now has a **.binlog(bool)** function (logging off by default)
* Database now has **.begin()** and **.end()** methods (begin supports **with**)
* All **Table** functions should now be wrapped to ensure they're included in repl transactions
* ORM - we now have a built-in (optional) ORM with support for custom models and custom types
* ORM - includes support for calculated (virtual) fields and transparent many-to-many links
* Added README-ORM
* Main test suite was added to and transaction testing added
* Two new suites were added for model and ORM testing
* Tidied up some of the examples and benchmark
* Updated README to include link to ORM docs and sample benchmark results

* Fixed bug in 'seek' where the index key rather than the primary key was returned in the record body
* Clean up exception handling on append
* Fix append to allow the use of user-generated _id's
* Facilitate environment-wide txn

* Updated range code to include None as a possible upper and/or lower limit

* Added three new test cases
* Added "inclusive" option to table.range, set False to exclude matching keys at
each end of the range results.

* _id no longer stored in record body (removes duplication)
* Removes unnecessary decode in range
* Lots of misc bug fixes and exception fixes
* New Readme
* Added seek_one function
* Switched from UUID to bson.**ObjectId**