Check all userid's within a key to see if they match the current email rather than just the primary email
Updated signing code to find any valid master key and then check all of it's userid's to check if the sender email matches
Merge pull request #3 from Omegaice/sign_account

Signing with secondary userid emails.
Merge pull request #4 from Omegaice/subkey_verify

Secondary userid verification
Merge branch 'master' of github.com:Airmail/Airmail-Plug-In-Framework into develop

* 'master' of github.com:Airmail/Airmail-Plug-In-Framework:
  Updated signing code to find any valid master key and then check all of it's userid's to check if the sender email matches
  Check all userid's within a key to see if they match the current email rather than just the primary email