- Copy stable/10@285827 to releng/10.2 in preparation for 10.2-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.2.
- Update default pkg(8) configuration to use the quarterly branch.[1]

Discussed with: re, portmgr [1]
Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC r284333:
Reduce the arm/armv6 image size from 1G to 480M.

Since the images are effectively mostly zeros at 1G,
reduce the size to allow installation on smaller SD
cards, such as 512Mb.

While here, stop writing the /boot.txt file on the
WANDBOARD, which isn't used anyway.

Sponsored by: The FreeBSD Foundation

MFC r283920, r283991, r283992, r284102:

r283920:
Add a configuration file to support the Cubox/Hummingboard SoC.

r283991:
Add initial support for building images for the Duovero Gumstix
board.

r283992:
Fix a whitespace nit.

r284102:
Set the correct UBLDR_LOADADDR for the Wandboard and
Cubox/Hummingboard images.

Sponsored by: The FreeBSD Foundation

Add a configuration file to support the Cubox/Hummingboard SoC.

Sponsored by: The FreeBSD Foundation