Remove extra test flags from all commands

Currently all commands are being build with extra flags.
The extra flags appear because of a direct import of the
testing package from the fake_etcd_client.go source file.

Remove the direct import of the testing package and refactor
related tests not to rely on its use. Also clean up two TODO
items by remove using of the expectError and expectNoError
functions.

Fixes #579
Great suggestion. I'll work on that.