Bug 912904 - [System][Dialogs][ActionMenu] Dialogs & Action menus (BB) a...

...re not scrolling as expected when there is a large list of items. r=alive,kaze

This patch fixes Gaia part. As well fix an issue with Card_View unit tests.
Before landing this patch GAIA_UI_TEST should be fixed. For doing this we should to modify:
https://github.com/mozilla/gaia-ui-tests/blob/master/gaiatest/apps/settings/regions/display.py#L13
From_
_wallpaper_button_locator = (By.CSS_SELECTOR, "a[data-value='0']")
To:
_wallpaper_button_locator = (By.CSS_SELECTOR, "button[data-value='0']")