Add sanitizing function for mapping file

This function is called from the main script interface and it will
replace all of the ' or " characters with an escaped version that will
not affect javascript.

Test module was updated accordingly.

Closes #52
Move sanitizing to preprocess_mapping_file
Remove ' and " instead of escaping
Merge pull request #53 from ElDeveloper/issue_52

Add sanitizing function for mapping file  -- fixes issue 52