Roll back to v0.25, keeping the master branch usable.  New development is moved to the js-rewrite branch.

Reverts:
- "Early implementation of jwPlayer 5." / 765f76966b2efadf24a8781179d5c80b58140165.
- "Use jquery instead of document.getelementbyid calls." / cae3c7aa0d9e00c102a92706e4e9d0c01c53b109.
- "Work in progress: Rewrite to a simpler PHP backend." / 4d2d3a1a67d47b8765d979d6624588ec6763675c.