Progress commit - refactor metadata and schemas.

Moving to an SQLAlchemy model for storage of reflected db metadata.
added sample database and started writing some unit tests.
Broke metadata.py up into a package, it was getting too fat.
uneeded file
progress commit - broken and slow things
progress commit: fix completion. add indexes to %describe output
fix %fks and %references
fix %fields for new metadata
Fix bug with join expression expansion
rename of completion_accessor
turn off debuggering
cleanup. fix bug with show_fields()
ignore
Merge branch 'master' of github.com:jaysw/ipydb
Merge branch 'refactor-metadata'

Conflicts:
	ipydb/metadata.py