Spell check our documentation.

There were a bunch of small typos in the docs. I've gone through with ispell
and checked everything in docs/manual.

Reviewed at https://reviews.reviewboard.org/r/5873/
Fix typos and spelling in release notes.

I ran ispell on all our old release notes and fixed all the problems.

Reviewed at https://reviews.reviewboard.org/r/5874/
Remove the old webtests.

We haven't maintained or even used the webtests in a long long time. The
more modern JavaScript unit tests are a better replacement for those
anyway. This removes the webtests from the codebase.

Reviewed at https://reviews.reviewboard.org/r/5878/