[bugfix] [shared/oval, RHEL/6, RHEL/7, Fedora]

Replace use of multiple (possibly outdated) versions of idtranslate.py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.