Add config_reload and config_override to test.c, change prompt.

Add config_reload and config_override to test.c, change prompt.

  PV         PV UUID                                VG
  /dev/loop1 A95EvV-iqmb-ZFuJ-u8MV-Npwn-wlc2-Ul1Mnn vg1
  /dev/loop0 R16FDG-OmoS-HNGt-LSZY-OAlC-7qeU-t2gztp vg1
lvm> config_override loop0
Success overriding LVM configuration
lvm> config_reload
Success reloading LVM configuration
lvm> vg_open vg1
Couldn't find device with uuid 'A95EvV-iqmb-ZFuJ-u8MV-Npwn-wlc2-Ul1Mnn'.
Success opening vg vg1
lvm> vg_close vg1
lvm> quit

Maybe a bug in lvm_vg_open for missing pvs but the filter seems to work.

Change prompt from "lvm>" to "liblvm>".

Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>