netinfo getIfaceCfg cleanup, naked except removal

getIfaceCfg was using shlex but not taking advantage that it
can handle comments better than we were doing (inline comments
and such). This patch makes heavier use of it as well as removes
the naked exceptions that were catching BaseExceptions (which
is usually evil).

Change-Id: I26112f41c72dbfb3b9c8cdb181cf731297d0e072
Signed-off-by: Antoni S. Puimedon <asegurap@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/17760
Reviewed-by: Giuseppe Vallarelli <gvallare@redhat.com>
Reviewed-by: Mark Wu <wudxw@linux.vnet.ibm.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>