Fixes #66 with coverage of unit test via travis. 

Hi, 

This PR have good and bad things.

Good

1. Removed the shell script
1. Better coverage of unit tests
1. Run phpunit from root without passing the directory

Bad

1. Unit test now relies on composer
1. require-dev of `aura/di` added.

I am not against this way of unit testing for users still can install `aura/router` via `--no-dev` if they don't like.

Let us move this way?

Thoughts ?
Well, let's keep it simple by echoing the message. Other libraries are doing the same already.

But the way to do it is ``fwrite(STDERR, 'Run composer install for testing' . PHP_EOL);``