Add Codelet, crawler dependencies to setup.

Add:
    bitshift/codelet.py
        -add Codelet class with constructor.

    README.md
        -add SASS stylesheet documentation
Minor refactor of codelet.

Add:
    bitshift/codelet.py
        -complete docstrings, add filename to Codelet constructor.
Docstrings for Database methods; oursql dependency.
Database schema, hashing module, some other things.
Some more database design work.
More work on db schema; all except FTS indices.
Remove languages table; add indexed field for codelet rank.
FULLTEXT KEYs where appropriate.
Fix some typos in the schema.
Move database stuff to a subpackage; updates.
Some more work on db stuff.
Update schema to v2; database updates.
Credits.
Finish migration to v2.
DB -> v3 for symbol->code assoc vs. ->codelet (fixes #13)
Flesh out most of Database.insert().
Database to v4: split off symbol_locations table.
Finish database insertion, except for origins.
Fix a couble Database bugs.
Database to v5; finish Database.insert().