Update post-public-admin.js

Use `'use strict'` statement, remove a call to addClass function, simplify wrapper code.
Leave out strict mode for now
Drop strict mode back in there, my reasoning for leaving it out is null and void
Update plugin header
Misc code quality tweaks
Remove unused methods
Remove outdated docs and tests - these will all need to be re-done
Remove unnecessary readme.txt
Remove .gitignore
Readme updates