The plaintext and ciphertext fields weren't showing up on Nexus 7
(possibly other devices too) because of some unresolvable dependencies
between UI elements.
Also stopped leaving these fields editable when no key was selected
and corresponding action buttons were switched off.
Change-Id: I32ed3e2f24c134504a02db6fdfb9905ec147fbdd
Adds a sample application which uses the AndroidKeyStore and
KeyPairGenerator for AndroidKeyStore.
Bug: 8608817
Change-Id: Iec78a74461dc259e4080ed1fab7d923593fcdf75