Tweak travis build

[maxime-rainville]

Fixing broken build introduce in #78

[jonom]

FYI, I tried with ^1.6 and 1.6.x-dev and both failed.

[jonom]

Maybe it should just be dev-master?

[maxime-rainville]

The problem was that there wasn't a minimum stability define in focus-point's composer.json. So it implicitly defaulted to stable. I've tweak it to say that dev dependencies are allowed. This should allow the travis build to install the dev branches.

Note that this change won't make any difference for people installing focus point on their project. Composer only honours the minimum stability of the root composer.json file.

The build is still failing but those failures were pre-existing. I got these errors while I was developing #78 and running the test locally.

[jonom]

Perfect, that did the trick. Thanks for your help. Yes there was an existing build failure, going to revert the cause of that and then we'll be green again.