Support $X-Request-Base for the Logo

Dependencies

• [2] JINQDKLI Don't always include "Hydra" in the logo part.
• [3] F6LBAQML Fix logo size
• [4] G4X5IUYJ Remove default logo, replaced by text for now. Hide template in jobset edit.
• [*] J5UVLXOK * Start of a basic Catalyst web interface.

Change contents

• replacement in src/root/layout.tt at line 60
  [3.32]→[3.604:673](∅→∅),[2.75]→[3.604:673](∅→∅),[3.604]→[3.604:673](∅→∅)
  − <img src="[% logo %]" alt="Hydra Logo" class="logo" />
  [2.75]

  [3.33]
  + <img src="[% c.uri_for(logo) %]" alt="Hydra Logo" class="logo" />