lseek was triggering a number overflow by converting long to integer on
its return value

Added specific lseek test

Write errors happenig on deamons are now reported back to clients.
"No space left on device" error is now properly propagated to clients.

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"
```

 - Use regular expression to parse lines
 - More consistent error handling
 - More comprehensive error messages

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