Specify the ADB keys to use for ADB

In the golo, specifically, the adb keys used by swarming
are different than those used in the docker instance, unless
configured otherwise.

This means swarming can think a device is ready (authorized)
but the adb we called was not (authorized)

BUG: 843284
Change-Id: I697d5075258a176e7fc7a4b51a9e2c926e1b8fd0
Reviewed-on: https://skia-review.googlesource.com/128930
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
55 files changed