Initial support for unit tests

[tresf]

Throughout the years, we've written various unit tests, but never took the effort to standardize them.

With the huge refactor in #1391, we decided to implement the TestNG framework which can run these tests automatically.

Use: (subject to change)

ant testng

... optionally you can click the "Run" button next to execute a singular test directly from within IntelliJ.

Sample output:

   [testng] ===============================================
   [testng] Ant suite
   [testng] Total tests run: 27, Failures: 5, Skips: 8
   [testng] ===============================================

This exposes some issues with the codebase which should be addressed before merge:

• RawImageTests for HTML fail, likely to to slight differences in font rendering between platforms
• RawImageTests CPCL tests are failing now.
• Ant tasks compile-socket, complile-test, and <testng .../> have many redundancies now and should be refactored.
• Many classes in test don't yet leverage the @Test interface and need to be refactored.
• compile-socket creates a redundant copy of our .class files in out/qz-tray, which causes confusing when trying to locate the output files. We may want to nuke this redundancy to avoid confusion in the future.