Update head/ to ALPHA6 in preparation of branching to stable/10.

Approved by:	re (implicit)
Sponsored by:	The FreeBSD Foundation
New committer info.

Approved by:	re@ (gjb)
Approved by:	davidch (mentor)
Turn it all the way up to 11:

- Update FreeBSD version in:
  - UPDATING
  - sys/conf/newvers.sh

- Add 11.0 FreeBSD version for manual pages

- Bump __FreeBSD_version to 1100000

Approved by:	re (implicit)
Sponsored by:	The FreeBSD Foundation