Remove debug line.
Add test coverage for getConfigSources()

       Note that one test fails: One file is being returned twice in
       one case, and that looks like a bug.
REmove dead code for original/new values.

These values appear to be used nowhere and the tests pass when these
lines are removed.
Make modification of global variables self-contained to avoid cross-test interaction.

Tests were previously failing in strange ways because all the test files
were getting require'd before they are run, and all the 'process.env'
modifications were being triggered at require-time.

The modifications to these globals in one test were being overwritten by
the modifications in the other tests.

This patch moves the global modification into an explicit first
`addBatch` block, or specific topic blocks so they global variables
get set at run-time, just before they are used.
Simplify use of 'topic'.

All tests that refer to the global CONFIG object now do so consistenty.
Merge pull request #171 from markstos/add-tests-for-getConfigSources

Add test coverage for getConfigSources() (contains failing test!)