Make Ganesha honor install prefix

Currently, Ganesha has hard-coded locations of some of it's files, most
noteably it's configuration file.  Ganesha can be installed in an
alternate prefix, but it cannot run from that prefix without command
line options.

Change those hard-coded paths to indirect through SYSCONFDIR and
SYSSTATEDIR, so that Ganesha by default runs out of it's prefix.

Because cmake only has one install prefix (CMAKE_INSTALL_PREFIX), it is
difficult to properly install into the root of a filesystem.  To work
around this, Ganesha now by default installs into /usr, with config in
/etc/ganesha, and state in /var/run.  If CMAKE_INSTALL_PREFIX is set,
than it installs into bin/, lib/, etc, share/ and var/ inside that
prefix as normal.  DESTDIR= installs also work correctly in both cases.

Signed-off-by: Daniel Gryniewicz <dang@linuxbox.com>
Tested-off-by: Neils de Vos <ndevos@redhat.com>
Install a default ganesha.conf file

- Convert the vfs.conf file so it cannot run by default, rather than
  having it export /home
- Install it in the proper prefix location, makeing sure not to clobber
  any existing config file

Signed-off-by: Daniel Gryniewicz <dang@linuxbox.com>
Tested-off-by: Neils de Vos <ndevos@redhat.com>
Install config_samples into /usr/share/doc

Signed-off-by: Daniel Gryniewicz <dang@linuxbox.com>
Tested-off-by: Neils de Vos <ndevos@redhat.com>
Fix the spec file to work with the new install prefix

Signed-off-by: Daniel Gryniewicz <dang@linuxbox.com>
Tested-off-by: Neils de Vos <ndevos@redhat.com>