libxcmd: move error messages to appropriate place

libxcmd: move error messages to appropriate place

Replace raw perror() with proper message in
fs_table_initialise_mounts().

Replace raw perror() with proper message and move it from
fs_mount_point_from_path() to fs_table_initialise_projects() where this
message has meaning.

Signed-off-by: Arkadiusz Miśkiewicz <arekm@maven.pl>
Reviewed-by: Nathan Scott <nscott@aconex.com>
Reviewed-by: Donald Douwsma <ddouwsma@bigpond.net.au>