Add missing / Avoids potential problem of it not seeing an existing cache, depending on the CWD on the cache drive at the point the target is running (which could be anything really).

Turned on use of cache for all platform builds (unless over-ridden by the particular job properties of course).

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.