Logged in delegates should be able to claim the member they represent

[MaxwellBo]

Once they have claimed their member, we can then allow:

1. Delegates to delete their own strawpoll options (and only their strawpoll options)
2. Delegates to delete their own posts (and only their posts)
3. Select the country that they represent, which will:
   i. Remove the Poster dropdown on the Posts screen (preventing impersonation)
   ii. Remove the Queue dropdown on the Caucus screen (preventing accidentally queueing another delegate)