CP-4277: Allow unsigned patches to be installable

This is controlled by the presence of the hotfix file's sha1sum
in the FIST-point "allowed_unsigned_patches".

Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
Merge pull request #1191 from robhoes/cp4277-san

SANIBEL-LCM: CP-4277: Allow unsigned patches to be installable