Doc: Set homepage and build version in qdocconf

-QDoc creates a link to the homepage on each page.
-build version lets readers know the version of the manual.
-not really relevant when building with Qt 4.8, but it doesn't
 break 4.8-built documentation.

Change-Id: I70437c39e4bd5f209c1b6cab5ac7c795fb3d44ad
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>