Fake Mode, Ability to just print sql statement without real insert to the db

[ishehata]

• Allow users to call gofixtures and print sql statements of data read from the file without really inserting anything to a db.

this could be useful for someone, although i am not sure if there is a real case for this.

• maybe just create a new fake Postgres DAL, which is just a struct that implements the datastore interface and does nothing but printing the sql statements.