Bug 724633 - Migrate foundation pages to bedrock

I've kept it as two commits to separate my work from @dpoirier's in the history but we can squash them together.

Some of the formatting isn't as tidy as it could be, but I think a lot of these pages are way outdated and possibly redundant. We should get someone from the Foundation to review all this content some time soon and we may be able to cut down this whole section. This migration is just a straight copy from the old PHP site.