Workaround for Unsigned MapR Repos

I added the `--force-yes` flag to all MapR package installs for now just to get
this cookbook working.  I also found a small hindrance in the stock Ubuntu SysV 
init scripts for rpcbind.  They were just exiting whenever given actions: `start`, `restart`, or `stop`.
I'm not sure why this is in there, but it is:


        start)
            if init_is_upstart; then
                exit 1
            fi
            start $OPTIONS
            ;;
        stop)
            if init_is_upstart; then
                exit 0
            fi
            stop
            ;;
        restart|force-reload)
            if init_is_upstart; then
                exit 1
            fi
            stop
            start $OPTIONS
            ;;

To workaround the init script not doing anything except causing us problems, 
I just specified to use the Upstart provider for Ubuntu.

NOTE: We should revert commit 6e788f3 once MapR Ubuntu repos have proper key signing for security.
      I've added a note to the commit message along the same lines.