Fix bugs causing get.py to fail

[usmanatron]

Running get.py didn't work for a number of reasons:

1. The json file name was wrong - updated to point to the right file
2. The oakcli package has it's hash in uppercase; this mae the script thing the hashes were wrong when they were in fact fine. Added appropriate .lower()s
3. Again with the oakCli package, the regex fails to find a group, causing an exception. I've added some guarding around that area so that, if there isn't a regex match, it carries on without renaming. I think the problem is because the folder in the archive is "0.9.0" - if it had letters at the start we'd be fine!
4. Added support for .bz2 archives, used by bossac

[usmanatron]

Note: this is a pre-requisite for ISSUE-32 as we use this file to setup our build environment

[digistump]

Thanks - I had never bothered with keeping this up to date since it wasn't used before, great idea to use this to setup the build enviro!