Remove exc handlers for NameError and Keyerror in bin/crab
Remove blank lines from userfiles. Fixes #4267
Code needed to inject dependencies into CRABClient

Ideally, testing involves both unittesting (doesn't touch external
services) and fuller testing (sometimes called integration testing).
This is a first step to allow testing with external services by
injecting "fake" classes that look and feel like external services
Lazy-load external dependencies
Merge pull request #4276 from mmascher/melo-library

Recent Client changes