Some tests, more README, updated a few dependencies

Hi mericano1,

I came across your fork while learning about postgres, thanks for open sourcing your changes. I've made a few updates to the code that you may like to merge back into your fork: 
1. I've added some tests using ScalaTest. It's not a large amount if coverage, but just enough to test adding a task and reading it back.
2. I've updated the travis build file so that it installs postgres on the build server and run the tests.
3. Updated a few dependencies.
4. I had problems with the auto-increment on the primary key, so I moved the logic out into the addTask function.

The application.conf and travis.yml have been changed to the settings that "work on my machine", so if you accept the merge the first thing you will probably want to do is change those settings back to your own values.

Best regards,

scottkwalker