Separate git_fetch_repo_data.sh and multi_repository.xml generation

Right now git_fetch_repo_data.sh is doing both fetching and generating the multi_repository.xml.

These should be separated into two scripts.
They should also be set to different timers in inputs.conf.

The multi_repository generating script should only have to be run at start-up/configuration change.
git_fetch_repo_data.sh could be run all the time, or intervals of maybe 20-30secs?
