zerocloud, all modules: one import per line

Instead of using commas and backslashes for line continuation, having
just one import per line improves readability.

It's also easier to edit imports this way; you can just add or remove
lines. When changes like this are made, the diffs are more readable as
well.
Merge pull request #156 from larsbutler/one-import-per-line

zerocloud, all modules: one import per line