Ensure all backends have automated tests

[brainwane]

Of the several maintained backends, only two (Launchpad and Allura) have automated tests, and those are limited, and written in different ways. So I suggest we:

• put test data for all backends into the tests/data/ directory
• write tests for the data-processing parts of all maintained backends, using Python's unittest framework (could also use Mock and nose)
• port the Launchpad tests to use the standard framework instead of having to download data from the web each time