Passing ?limit=0 to the blueprints/list, blueprints/changes,
projects/list, modules/list should always return the total possible
results, not 0.
Also move the composer-cli test_diff to the end so that it will work
consistently. Do this by naming it test_z_diff.
This adds empty __init__.py to tests so that a lib.py library of helper
functions can be imported from the tests.
Add captured_output to use with composer-cli tests to capture stdout/err
output from the functions.
Some results have errors and no status, others have status and errors.
Update the function to return the final rc to exit with, and a bool
indicating whether or not to continue processing the other fields.
Add a bunch of tests for the new function to make sure I have the logic
correct.
