Add a travis configuration file.

Hello!
This pull request would add a [Travis](https://www.travis-ci.org) configuration file, so that tests get run automatically on a Travis computer every time a commit gets pushed.

(you would also need to 
* log in to Travis with Github OAuth,
* go to your profile page, 
* flip clatrix's switch on,
* copy your token string and finally
* go to the github service hooks page and paste your username and Travis token string [as explained much more eloquently here)](http://about.travis-ci.org/docs/user/getting-started/#Step-one%3A-Sign-in)

I would also like to ask whether a stable version that includes ``` clatrix.core/det ``` is coming out soon. :smiling_imp: 

Cheers!