fixed up Ruby based on review

The following optimizations were performed:

- Add new association to GroupMember and ProjectMember

  This new association will allow us to check if a user is a member of a
  Project or Group through a single query instead of two.

- Optimize retrieving of Members when adding multiple Users

the position of the popover is correctly calculated and positioned to
the bottom when the navigation would overlap the popover.

since all the signature badge templates now have more or less the same
content we can push most of it down to the main template `_signature_badge`.

this is used to make a difference between a committer email that belongs
to user, where the user used a different email for the gpg key. this
means that the user is the same, but a different, unverified email is
used for the signature.

the updated verification of a gpg signature requires the committer's
email to also match the user's and the key's emails.

we need the commit object for the updated verification that also checks
the committer's email to match the gpg key and user's emails.

This changes the issue and MR index pages so the pagination system
re-uses the output of the COUNT(*) query used to calculate the number of
rows per state (opened, closed, etc). This removes the need for an
additional COUNT(*) on both pages.