Add Travis CI build?

[FranklinChen]

It might be a good idea to add a Travis CI build. I just did npm install and it failed at

> install-purescript --purs-ver=0.12.5

so something's wrong.

[thomashoneyman]

I agree, this should have a continuous integration build. I'm most familiar with Circle CI, but I'm also open to Travis. I can do this at some point soon, but if anyone else would like to submit this as PR I welcome that, too!

With regards to your failure installing PureScript, I should have updated the dependency to be purescript: 0.13.2 and overlooked it. You're right that this could be caught by continuous integration.

In this case, I believe you're seeing a failure because of this problem with the NPM installer for PureScript. Installing PureScript 0.13.2 should work instead.

I've updated the dependency in the master branch if you'd like to checkout again.

[thomashoneyman]

@FranklinChen I've added continuous integration via Circle CI and a badge to the README displaying the build status. Thanks for the suggestion!