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.
-  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. My original intention was to use bash to scrape the console output but this would've been finicky because the console output is likely to change, and it's not easy for bash to work with doubles.

Comments:
- You should be able to see whether the Travis CI build of the current pull request is successful or not below. 
- Current Runtimes of Script (integration-test.sh)
    - Part 1 -- Compilation (7s)
    - Part 2 -- JUnit Test (8s)
    - Part 3 -- Run Examples (32s for 1 sample, 35.5 s for 10 samples, 53s for 100 samples)
Good doc :+1: