Android: Tweaks for --wait-for-java-debugger

* Add the flag to junit tests
* Better log statements
* Updated docs

Change-Id: If967015a697ef6a840f26f2311768230b874ab46
Reviewed-on: https://chromium-review.googlesource.com/786970
Commit-Queue: agrieve <agrieve@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#519007}
6 files changed