Closes #1162: Problems with codeviewer

 - added String#encode in codeviewer.rjs
fix the mistake with page.replace_html
Merge pull request #1167 from GhiGt/codeviewer-escaped

Closes #1162: Problems with codeviewer
Added utf-8 setting in db/schema.rb
Fix: added utf-8 header
Quick fix for adding instructors with rake task using ruby 1.9.3