Continuos integration for Travis-CI

This PR implements a continuos integration process for Sproutcore using the freely available service Travis-CI.

The changes are:
1. a travis.yml configuration files required by the Travis-CI commit hook to know how to build and test the software
2. a shell script which starts sc-server from the local copy of the sources. The script can also be used on developer workstations to quickly test SC on master. I use it on http://c9.io
3. a phantomjs test runner which basically runs all the test files in the Sproutcore source tree (experimental has been excluded for now)

Sample results: https://travis-ci.org/unicolet/sproutcore

What needs to be done:
1. consensus on script names and location
2. prettify the phantomjs runner
3. apply https://github.com/sproutcore/sproutcore/pull/1018
4. perhaps add an option to exclude known-to-be-broken tests from triggering a failure
5. fix broken tests ;-)