Updates for v0.10

Live preview: http://bitcointest1.us.to/en/download

- Release notes still need to be added.
- 2014-12-01-v0.10.md needs to be renamed with the right date on the day of the release.

This pull request makes required changes the download page for v0.10 and all texts refering to the long synchronization time. It should be merged when v0.10 will be released in the next month(s).

Changes in this pull request:

- Set filenames once in the download page
- Edit download page for new or updated files
- Add link to the source code, GitHub and torrent download
- Drop mentions of long sync time everywhere
- Add short instructions to run a full node on the download page