Upgrade VR keyboard APK version

Regular upgrade to current VR keyboard release version.

TBR=bajones@chromuim.org

Change-Id: I02cd2e6dbdc316387461c1f2c0ae3380051ee1dc
Reviewed-on: https://chromium-review.googlesource.com/1226356Reviewed-by: Brian Sheedy <bsheedy@chromium.org>
Commit-Queue: Brian Sheedy <bsheedy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#591394}

third_party/gvr-android-sdk/test-apks/vr_keyboard/apk_version_history.txt

 v1.12 a31ceb898c8179e8bda976ff45e497848b9ba0be
 v1.13 0fe388ce58b14909cdc9ee045f07076581491629
 v1.16 56ca300b7d28a752ea24f89c1685f28e83a04002
+v1.17 18ab8790479447a9d0b7768c7eb5420ecbfd70a2

third_party/gvr-android-sdk/test-apks/vr_keyboard/vr_keyboard_current.apk.sha1

-56ca300b7d28a752ea24f89c1685f28e83a04002
+18ab8790479447a9d0b7768c7eb5420ecbfd70a2
\ No newline at end of file