[VVP] Added new three new reports

Resolves VVP-81 by introducing three new reports to the validation
script output.

Each report is written to the output directory under ice_validator.

* mapping_errors.csv - each row represents an issue where a test is
                       mapped to a requirement that does not exist
                       in the requirement.json file
* traceability.csv   - Shows a mapping between all test cases and
                       requirements.  Rows will also be shown
                       where a requirement does not have a tests, and
                       where tests are not mapped to a requirement
* report.{html|csv|xlsx} - Formatted error report that shows each
                           failure that was detected and maps it to
                           a the file name, requirement(s) violated if
                           known, possible resolution steps, error
                           message, and raw output from pytest.  The
                           report can be written in html, csv, or Excel
                           format

Other minor changes:
* Replaced smart quotes with regular quotes to resolve issues with py3
* Updated copyright of modified files
* Fixed Flake-8 errors

Issue-ID: VVP-81

Change-Id: I659836cb20262ae44652c03639281a817dd051ae
Signed-off-by: Lovett, Trevor (tl2972) <tl2972@att.com>