Overload __deepcopy__ for compatibility with copy.deepcopy

Add trivial tests for this functionality.
Merge branch 'deepcopy'
Add test for `dicti.pop`

The test demonstrates the faulty interaction with current
implementations of `MutableMapping.pop`.
Fix `dicti.pop` by reimplementing `MutableMapping.pop`

It could also be done by subclassing `MutableMapping`, but I am unsure
whether that is a good idea.
Merge branch 'fix-pop'

Conflicts:
	test_pydicti.py
Add setup.cfg for nosetests
Cosmetic fixes
Convert README to reStructuredText

reST READMEs interact better with PyPI.
Include test_pydicti.py in source distributions
Merge branch 'cosmetics'
New minor version

CHANGES:

 - fix dicti.pop
 - support deepcopy(dicti)
 - make nosetest automatically execute the doctests