We don't want the log file to be created before command line parsing,
otherwise --version or --help cli option could not work beacause we
don't have permission to write to log file.

Port is only meaningful for some of the communication protocols. For
instance psm2 is not using it at all.

Port can be still specified using the --listen,-l flag:

Example:
```
gkfs_daemon --listen "localhost:1234"
```

Shared-memory communication can be disabled through cmake
compile time option `-DUSE_SHM:BOOL=OFF`

Refactored initialization code.

 - More detailed logging
 - Use exceptions to better propagate errors
 - Log signal type before shutdown

Daemon is now capable of providing version information through the
`--version` cli option.

Get rid of all the occurrences of old project name "adafs" from output
strings and documentation

get rid of adafs name from folder names

A new cli parameter `--listen`,`-l` allow to specify binding address/interface

RPC port can now be configured at runtime through `--bind-port` command line argument.

For some comunication layers an out of band communication is required for putting in place the specific protocol handshake.

In those case a shared lookup file could be used to distribute deamon's endpoints information to all the clients.

This file need to resides on a shared filesystem and can be specified using the new CLI parameter `--lookup-file`.

When the pid file already exists don't try to kill the previously
running daemon. Just print an error and exit.

gid and uid metadata fields have never been used and can be removed
safely

The access RPC have been removed. The POSIX access functionality now is implemented through the stat RPC. This makes code easier to maintain and modify.

There would be a little performance degradation on the POSIX access
function because we are now retrieving also the metadata
associated to the file.

This change makes a lot easier to add symlink support

 - improved statfs system call
 - intercepted statvfs library call

Both of the above function now report the aggregated real size
of all the data-nodes.

You can test this with `df "/tmp/gekkofs_mountpoint"` command

Changes have been merged upstream [1] with commit `acb8c296a694d7e3e06756e7a102a9d1c92df0c8`.
There is no more need to patch margo to expose enanched init function.

[1]: https://xgitlab.cels.anl.gov/sds/margo/merge_requests/9

Paths passed as parameter to the daemon needs to be canonicalized

Since now there is only one margo instance there is no more difference
between RPC and IPC.

All the "ipc" occurence in the code have been removed in favor of "rpc"

the functionality wasn't used at all and it will be implemented later
with a different approach

Instead of passing only the mode as paramenter, we now pass an entire
Metadata object in such a way that the parameter can be configured at
compile time. For instace if we support symlinks we would like also to
pass the target path