Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

Remove the HH-MM suffix from the build date suffix.

It was useful when working out several kinks when
testing automated image uploading when retrying was
necessary, but now it is making things much too messy.

MFC after: 3 days
Sponsored by: The FreeBSD Foundation

Change the hour:minute delimiter from ':' to '-', since
the former is an invalid character in EC2 images.

MFC after: 3 days
Sponsored by: The FreeBSD Foundation

Consider PRERELEASE builds snapshots, in addition to CURRENT and
STABLE.

MFC after: 3 days
Sponsored by: The FreeBSD Foundation

Append the hour and minute to the snapshot suffix for EC2
AMIs and Azure VM images. This is particularly helpful for
testing to avoid name collisions, but also useful for cases
where a necessary rebuild is done before the date changes.

MFC after: 3 days
Sponsored by: The FreeBSD Foundation

Add Makefile.azure, used to upload VHD images to the
Microsoft Azure environment, similar to the EC2 AMIs.

MFC after: 3 days
Tested with: stable/10@r284517 (patched)
Sponsored by: The FreeBSD Foundation