Apply a giant code cleanup.

Essentially:

- Remove unused code.

- Make it 'go vet' clean. The only remaining warnings are in generated code.

- Make it 'golint' clean. The only remaining warnings are in gerenated code.

- Smoothed out same minor things.

Change-Id: I3fe5c1fbead27b0e7a9c247fee2f5a45bc2d42c6
Fix typos and import order.

This doesn't make the import order consistend everywhere, just where
it was touched by the previous commit.

Change-Id: I82fc75f8691da9901c7ceb808e6f6fe8e5d62c0e
Merge pull request #421 from prometheus/u-c-l/code-cleanup

Apply a giant code cleanup.