Mostly-completed (not 100%) GSS example.
Merge branch 'release-0.2.0'

Conflicts:
	docs/examples.rst
Optimize estimate pairwise, and add plumbing for connected components
Connected components working, and fixed a nasty bug in estimate pairwise for columns
Add BayesDB Error framework, and fix output extra line.
Add BayesDB errors to cover column parse errors, and clean up BayesDB error handling.
Fix bug in connected components
Add more error message coverage
Merge branch 'master' into analyze