Adds Notes to Creds

This requires a small modification to the gem metasploit_data_models.
This branch patches the cache but the changes are also in a forked
version of the gem here: https://github.com/zombieCraig/metasploit_data_models.git

I couldn't figure out how to initiate a migration but it is a small change that should work.

Original commit notes below:
This adds notes to Creds.  This is useful
for recording meta information about an account
such as groups an account belongs to or other things
from post intel gathering.  The migration file in
data/sql should work but was unaware of the proper method
to trigger a migration.

This patch allows for seamless integration when
specifying :user and :pass when calling report_note