Mark script as executable

When using maven and the maven assembly plugin, permissions are copied
from source files, and changing them seems to be complicated.

As such, make this script executable, so we can just "git submodule add"
this and mark the file as needed, as in
https://github.com/Fedict/eid-viewer/tree/master/eid-viewer-osx/src/main/resources

Author: yoe