Revert "Merge pull request #17 from oelmekki/allow_postgres_usage"

This reverts commit 5acb07019aa04d0f88e0e1c0d7f55681d13414a0, reversing
changes made to af8dbca25771aab6f062b1f1f3fd144364323573.

This is to undo temporary changes to allow running tests on
multiple databases, which will be covered by the configs
for TravisCI in forthcoming commits.
Configure the library for running on TravisCI

Removed dummy apps (we load the schema and models
necessary for testing). Added .travisci.yml with
a variety of environments to test. Added gemfiles
for rails 3, 4, and edge.
Don't allow failures anymore
Switch to RSpec
Isolate expectations
Fix query for Rails 3 where !=
Clean up expectations
Update README regarding testing

[ci skip]
Depend on ActiveRecord, not all of Rails
Merge pull request #18 from shekibobo/travis-setup

Run tests on Travis, on pretty much every environment