Merge pull request #6 from bhandfast/master

Made ContentValuesWrapper's put methods fluent.
Use the 'nullable' flag when generating code, to use nullable 
wrapper types (Integer, Long, etc.) or not nullable native types (int, 
long, etc.) when appropriate.
Avoid possible SQL injection when passing in multiple values.
Resolves issue #4.
Added a mandatory 'toolVersion' field in _config.json.
Bumped version to 1.4.
BaseColumns is an interface.
Fixed a few typos.