Portrait Mode header messed up

[ddfridley]

In portrait mode, the Undebate logo is missing, and the search icon is clipped.

• The search icon should not be shown when user is not logged in.
• The Instruction button should return null (for both portrait and landscape) as we have not implemented that yet.
• The Undebate logo should appear at the top left
• The sign up/log in button should appear on the right in portrait mode.