Add tests for some functionality of the crawler

[marco-c]

Maybe moving some crawler code in a separate module under the autowebcompat directory.

[poush]

I would like to work on this.

[marco-c]

I would like to work on this.

Sure, go ahead!

[poush]

@marco-c Need some help here. So on checking collect.py, I think read_sequence, get_all_attributes, screenshot, set_timeouts can be moved to autowebcompat directory and can be added in test cases. but get_all_attributes, set_timeouts and screenshot is driver module dependent which they receive as parameter. So is it right way of doing this or should I think and try again?

[marco-c]

For the functions that get a webdriver as parameter, you can create a webdriver in the test.