Resolve "New start and stop scripts"

This MR is part of issue #52 (closed) and introduces a beta version for a new script which can start and stop GekkoFS daemons. For consistency the env variable to control daemon log levels was change from GKFS_LOG_LEVEL to GKFS_DAEMON_LOG_LEVEL.

It supports all GekkoFS arguments, numactl, and srun, and it can be run in the foreground and background.

The help page is as follows:

usage: gkfs [-h/--help] [-r/--rootdir <path>] [-m/--mountdir <path>] [-a/--args <daemon_args>] [-f/--foreground <false>]
        [--srun <false>] [-n/--numnodes <jobsize>] [--cpuspertask <64>] [--numactl <false>] [-v/--verbose <false>]
        {start,stop}


    This script simplifies the starting and stopping GekkoFS daemons. If daemons are started on multiple nodes,
    a Slurm environment is required. The script looks for the 'gkfs.conf' file in the same directory where
    additional permanent configurations can be set.

    positional arguments:
            command                 Command to execute: 'start' and 'stop'

    optional arguments:
            -h, --help              Shows this help message and exits
            -r, --rootdir <path>    Providing the rootdir path for GekkoFS daemons.
            -m, --mountdir <path>   Providing the mountdir path for GekkoFS daemons.
            -a, --args <daemon_arguments>
                                    Add various additional daemon arguments, e.g., "-l ib0 -P ofi+psm2".
            -f, --foreground        Starts the script in the foreground. Daemons are stopped by pressing 'q'.
            --srun                  Use srun to start daemons on multiple nodes.
            -n, --numnodes <n>      GekkoFS daemons are started on n nodes.
                                    Nodelist is extracted from Slurm via the SLURM_JOB_ID env variable.
            --cpuspertask <#cores>  Set the number of cores the daemons can use. Must use '--srun'.
            --numactl               Use numactl for the daemon. Modify gkfs.conf for further numactl configurations.
            -v, --verbose           Increase verbosity