Audit unit test coverage

[arschles]

As of this writing, coverage is just over 50%. We should intelligently look for ways to increase it, then write the tests to do so.

[jackfrancis]

At the very least this issue will include bringing server_test.go.TestPostClusters up to speed with the standard idiom for this project. Don't use that as an excuse not to increase overall coverage!

[jackfrancis]

Update make test to include the -cover option so we can track coverage over time.

[arschles]

punting this to beta4

[arschles]

Moving this to RC1

[arschles]

Also note that test coverage has been significantly increased as the codebase has grown. We'll need to check the coverage again. I hope we can close this pretty early in the RC1 cycle.