Added some tests, cleanup constructor

Making way to a more testable library, and a --dry-run argument that return sql.

Update cli, using commander

Type gj2pg -h for cli help.

Using knex.js + new operations.

Using knex.js for this, since writing sql statements by hand isn't the best idea..

Also have -o which stands for operations, and is by default insert. Other possibilities are update and delete, which must make use of -p, for primary key.

-p columnName is set with the column name of the column in your database.

Add -v argument, for version

0.2.1

Merge branch 'master' of github.com:AppGeo/gj2pg