Database dumping feature and API/UI improvements.

csvsql command changes:

- Added the 'docopt' module as a dependency and used it for parameter parsing.
- Changed the output of SELECT queries to CSV.
- Added the ability to dump the database as a CSV.

csvsql.py changes:

- CSV import is now accomplished through the csvsql.import_new() class method.
- Existing CSV database initialization is now done in the csvsql() initializer.
  information.
- Wrapped data insertion duing CSV import with (permissive) exception handling.
- Added iteration support via __iter__().
- Added a __repr__() method to the csvsql class that returns more useful
  information.