Test Subproject

This pull request puts forth, for your enjoyment, a test project.

Specifically, a test subproject that aims to work with the Jenkins CI server the TAs/Marty set up.

I want everyone to check out this branch locally (assuming they have `ant` and the android tools set up and in their path) and try it out.

* `cd` into the `tests/` folder
* run `android update test-project -m ../ -p .` to set up your `local.properties` file
* Then you should run `ant unittests`
* If everything worked correctly, the build should fail with similar output at the end:

```
test:
     [echo] Running tests ...
     [exec] 
     [exec] com.example.budgetmanager.test.TestCaseBudget:.
     [exec] Failure in testIsBudgetGood:
     [exec] junit.framework.AssertionFailedError: Not yet implemented
     [exec] 	at com.example.budgetmanager.test.TestCaseBudget.testIsBudgetGood(TestCaseBudget.java:11)
     [exec] 	at java.lang.reflect.Method.invokeNative(Native Method)
     [exec] 	at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:190)
     [exec] 	at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:175)
     [exec] 	at android.test.InstrumentationTestRunner.onStart(InstrumentationTestRunner.java:555)
     [exec] 	at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1661)
     [exec] 
     [exec] Test results for InstrumentationTestRunner=..F
     [exec] Time: 0.005
     [exec] 
     [exec] FAILURES!!!
     [exec] Tests run: 2,  Failures: 1,  Errors: 0
     [exec] 
     [exec] 
     [echo] Checking for failures

BUILD FAILED
/path/to/the/project/tests/build.xml:98: Unit tests failed!
```

If you get anything else, then please say so since that means that the configuration on one of our ends is off.