Provide horizon tag during settings update

By default murano data was being added to the
horizon settings copy of master branch. Now a tag name,
representing horizon release could be provided.
If no tag is provided master branch is used

Usage:
./update_setting.sh --output="muranodashboard/settings.py" --tag=2014.1

Change-Id: Iec4d5d01a13330816e78179a5be1b516bf4f7e98
Closes-Bug: #1346399
Merge "Provide horizon tag during settings update"