[bugfix] [patch v#2] [shared/oval, RHEL/6, RHEL/7, Fedora] Replace use of multiple (possibly outdated) versions of idtranslate.py script by use of just one common instance

Replace use of multiple (possibly outdated) versions of idtranslate.py
script by use of one common instance. This patch performs the following:

* Replace use of multiple versions of idtranslate.py script with use of
  one common version,
* Replace use of multiple versions of testcheck.py script with use of
  one common module (testcheck_module.py) & multiple testcheck.py
  callers (from necessary places of the repository),
* Add .gitignore content for Fedora/input/checks & shared/ directories.

Tested on all three (RHEL6, RHEL7, Fedora) products & works fine.

Please review.