Rename index.css and require.js with md5 hash

- removes obsolete "cache buster" setting
- replaces hardcoded require.js and index.cs filenames in settings
files with for non-dev build processes with variables.
- release and couchapp_deploy tasks now rename those two files to
include their hashes, and reference them in the generated index.html
file
only run saucelabs on master

run unit tests in advance