Rewrite mentions of ://merlin-platform.eu/annis/ to ://commul.eurac.edu/annis/merlin

Fix #12

Quick and dirty (automatically):
```bash
find ./ -type f -iname '*.php' -exec sed -i -e 's#://merlin-platform.eu/annis#://commul.eurac.edu/annis/merlin#g' {} \;
```