Fixing some stuff

- Fixed problems with media source 1 not pointing to base path (ehelper
creating folder structure outgoing from the ms path)
- Added system setting "elementhelper.source" to specify which media
source should be used for the static files
- Added german translation + added one string to the en lexicon for the
new system setting
Minor enhancements

- Fixed problems with media source 1 not pointing to base path (ehelper
creating folder structure outgoing from the ms path), making plugin
independent from media source 1 (through system setting)
- Added system setting "elementhelper.source" to specify which media
source should be used for the static files
- Added german translation + added one string to the en lexicon for the
new system setting
Cleanup my commit mess (sorry)

- Removed commented out code
- Found the already implemented functionality to pull in information
for the description field, changed it a little bit and make the key
string customizable via another system setting (added lexicon entries
too)
Fixed merge conflicts and tidied things up a bit
Added default description setting for elements created with files
Updated changelog and readme