Fix access checking in views

[jacobwegner]

• team_manage should implement a check similar to team_update
• the following views compare manager_access to a Team.MEMBER_ACCESS constant, rather than checking the member_access attr:
  • team_apply
  • team_accept
  • team_leave

[jacobwegner]

(also, the check in team_update differs from a similar check within decorators.manager_required and they could possibly be consolidated)