python-smartpm: Add basic knowledge of RPMSENSE_MISSINGOK

python-smartpm: Add basic knowledge of RPMSENSE_MISSINGOK

Currently smart does not support recommend dependencies.  Add the first set
of 'support' for RPMSENSE_MISSINGOK (the flag that makes something a
recommend).  This initial support ends up ignoring the recommendation, but is
written in a way that it will be the basis of eventual support.

(From OE-Core rev: 4f1f6d39803c94cf9ff55f0a4616e7a1703bcef6)

Signed-off-by: Mark Hatle <mark.hatle@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>