Using ignore_list to ignore script and kbd

There is no need to have specialized logic to ignore the script and kbd tags in the caps filter, it can be handled by the process_ignores function.

I have therefore added both **script** and **kbd** as defaults to be ignored in the *process_ignores* function, and removed the logic from the caps filter. Not only does this simplify the logic of caps, but on a higher level, it is a good idea to make sure that typogrify does not ever touch things like the script.

I have also added more tests, and moved some tests around. I am pleased to say that everything passes.

@chrisdrackett This is a great first step in simplifying the code, but while all the tests pass, you need to convince yourself that this is the way to go. I am available for discussions. The next step (which I will do if you are okay with this) is to use the smartypants tokenizer logic to skip html tags. This will simplify regex and logic of things like the amp filter.