fixed path in webmail/lib.py

If you had moved your MEDIA_ROOT somewhere else, this wouldn't have
worked probably.
fixed typi
Revert "fixed typi"

This reverts commit b693bc82a9bdf9452277787cbddb64700a084891.
fixed typo
Merge pull request #2 from SimonKern/master

Media path issue in extensions/webmail/lib.py