Added .travis.yml file for TravisCI

[caciobanu]

No description provided.

[redthor]

Great job @caciobanu !

Just a couple of things:

• The build passed but there were two errors in this build. I am not sure if they're important:
  • this job is running on container-based infrastructure, which does not allow use of 'sudo',
  • PHP Strict standards: Declaration of AntiMattr\Tests\MongoDB\Migrations\Tools\Console\Command\StatusCommandStub::getMigrationConfiguration() should be compatible with that of AntiMattr\MongoDB\Migrations\Tools\Console\Command\AbstractCommand::getMigrationConfiguration() in /home/travis/build/doesntmattr/mongodb-migrations/tests/AntiMattr/Tests/MongoDB/Migrations/Tools/Console/Command/StatusCommandTest.php on line 218
• could we get a 'build status' logo in the README?

[caciobanu]

My answers below:

• The first one is not an error but an info message to not use sudo if a specific config is not set.
• For the PHP strict standards error I'll send another PR.
• I will send a separate PR for the README update.

PS: I wanted to keep CI integration changes as minimal as possible so for future PR`s we have CI up and running.

[redthor]

I did the README update in #7