Be more dynamic finding partitions for install

/disk/by-* isn't always ${disk}${part} or ${disk}p${part}. Add
additional patterns.

Change-Id: I9eb95b0f30305b9b7184184d1106d5f037ebc363
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1051742
Signed-off-by: Ryan Barry <rbarry@redhat.com>