New functions to facilitate the writing of CLI test cases

New functions to facilitate the writing of CLI test cases

Writing CLI test cases is tedious because of all the formatting and
escaping subtleties needed when comparing actual output with what's
expected. While creating a test case the two new functions are to be
used instead of the existing execute() in order to prepare the correct
command and expected output and to generate the corresponding test code
that can be pasted into the test case function.

Change-Id: Ia66dc449d3f6fb861c300fef8b56fba83a56c94c
Signed-off-by: Chris Aniszczyk <zx@twitter.com>