Merge pull request #952 from ablake/next

Gamepad form input changes.
Gamepad can return from getJoystickValues and getTriggerValue if the control doesn't exist, rather than assert that it does.  This simplifies some code e.g. in the samples.
Changing the default setting of consumeInputEvents to 'true' for all controls.
Tweaking the forms in the sample browser and particles sample, as well as virtual gamepad behaviour, accordingly.
Merge branch 'next' of https://github.com/blackberry/GamePlay into next