[SCM] Write hook to prevent write to master, etc

[jamoore]

To enforce our policies about writing to the "release" branches, there should be a post-receive hook.

[jmoore]

Added the following to the bottom of the default update hook:

deny_user(){
    if test \! \( "$USER" = "jmoore" -o "$USER" = "cxallan" \); then
        echo ""
        echo "********************************************"
        echo "Modification not allowed to $refname by $USER"
        echo "Instead, use branch: $1"
        echo "********************************************"
        echo ""
        exit 1
    fi
}

case "$refname" in
        refs/heads/master) deny_user develop;;
        refs/heads/4_2) deny_user dev_4_2;;
        refs/heads/4_1) deny_user dev_4_1;;
esac

the names can of course be changed, but for the moment, this should hopefully prevent any accidental commits.