Adds unittests to the project

[karlcow]

This was a one-off script, but if this becomes something more used/usable we probably need to pour a bit of testing into it.

• create a tests directory.
• create tests for the main functions.
• optimize the functions if not testable as-is.

[skulltech]

Which framework should we use for testing? I think pytest would be good.

[karlcow]

Yeah pytest is fun, but on webcompat.com, we use unittest from python directly and nose to run the tests. For simplicity I would prefer we stick to this.

[skulltech]

Okay yeah, understandable.