Add recovery.img to multistrap release

* Additionally, check out beta-uboot before building recovery to ensure
it uses the uboot that prints the welcome message.
Change-Id: Ie6a84fd4a1afa225485d331656141b2c2fa1d089
(cherry picked from commit a05aee32669bcd3e0fad0762bfa70a8f2748e5d7)
1 file changed