Fix coverage configuration as per the docs at:
https://pypi.python.org/pypi/createcoverage/1.2
https://pypi.python.org/pypi/coveralls

Configure travis such that we only run the tests (once under coverage),
but only publish the results via coveralls on success.
Tidy up formatting
Move imports and functions from testing that were specific to benchmarks.
Make shadowtree.Node Implment BTrees.Interfaces.IDictionaryish
Add tests for magic methods and interface comformance.
Rename ARUIndexer to ObjectSecurity (reads nicer)
Rename adapter methods from reindexObjectSecurity
to just 'reindex' for readability and differentiation.
Adjust Spelling in module doc-string.
Re-work README to be more concise.
Update TODO.