Continuous integration

@lileicc @cberzan 

refer to #288 for original issue.

Implemented the following:
- Continuous integration script located in tools/testing/integration-test.sh
- Script tests compilation succeeds, all Junits pass (via sbt/sbt test), and all BLOG examples compile
- Script is integrated with Travis build so that if script returns a non-zero exit code, the travis build fails.
- pdf in tools/testing/docs/Integration Testing.pdf

Adjustments:
   - The following feature was abandoned: Verify that blog errors (parse error, nonexistent engine, file doesn't exit, etc) are caught and result in non-zero return code.
- Abandonment of the following feature was abandoned: A simple example (e.g. burglary) with fixed seed produces consistent output. The reason is because in src/test/java/test/example, there are tests that run for different examples, including burglary and hurricane, and assert the accuracy of the result within a certain bound.