Bug 1661: Simplified the sequence of pulls/clones via the cache, so the changes simply go from source -> cache -> destination. Made use of --uncompressed flag to speed things up. Including setting the flag when we create a cache entry.

Bug 1661: Improve build speed with better caching strategy Changed the way that the cache is located, so the same code can run on any build machine without any configuration. Made work around for Bug 419 the only option, as we're not using the alternative anyway, and I don't want to commit completely untested code! Changed caching algorithm, to improve build times.