Remove Ubuntu versions which aren't supported by upstream (rebased onto develop)



This is the same as gh-737 but rebased onto develop.

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13.04 is unsupported and doesn't have an openssl fix http://packages.ubuntu.com/raring/openssl
12.10 is supported but won't be after this month https://wiki.ubuntu.com/Releases
I think it makes sense to just drop anything not supported upstream even though they should work fine with OMERO.