Replace special characters in set name

WeBWorK doesn't like special character in the set name, so they have to
be replaced.
Add conversion of p tag
Merge branch 'master' of github.com:ubc/Blackboard-Learn-Assessment-to-Webwork-Converter
Support filename longer than 100 characters in tar

The default mode for tar in commons compress only support file name up
to 100 characters.