Adds SPICE HTML5 doc, fixes console section

partially fixes bug 1111126

WIP -  this does not build right now. Help welcome :)

SPICE HTML5 console support was added in Grizzly, this patch adds
a new section describing briefly why you would use SPICE over VNC,
and details its configuration options.

A new high-level section under interfaces we created for both to
live under.

The VNC console section has been reworked a little, to now include
the options from the table, which avoids a double-maintenance problem

patch2 adds a missing file

patch3 addresses comments from Daniel

patch4 adds a sentence about SPICE HTML5 arch, and removes hints that
       using both VNC and SPICE is possible :)

Patchset5 gets it building by further chunking which revealed a lack
of a <title> on one of the new sections.

Patchset6 just a rebase since Jenkins failed the prior patch.

Change-Id: I1437450dbfa943bfba92640c7d425d6a8ae40ac3
Merge "Adds SPICE HTML5 doc, fixes console section"