Rebuild all the unit tests

[shuaimu]

Previously all the unit tests are disabled to catch a deadline. Now it is time to bring it back. I am also thinking using a more accepted test framework, and it seems that google unit testing could be a nice choice.

And also adding travis-ci as auto-testing would be nice.

[lamontnelson]

I can get this working with the Google Testing framework. It'll be a good exercise while I'm getting familiar with the code.

[shuaimu]

That's Good! Many of the previous testing code simply don't work, if cannot be easily fixed, just leave them there.