MediaFocusControl: Do not grant audio focus if notification stream is 0

Previously audio focus would be granted regardless of notification volume, meaning
that if notifications are muted the media stream would still be dimished for focus.
By checking if STREAM_NOTIFICATION is 0 and if a notification stream is
requesting focus, this no longer an issue.

PS1: Initial implement
PS2: Better implement in MediaFocusControl
PS3: Whitespace

Change-Id: Ie10a64e58ce77174a3bbdeaa936646d40c24404f
Signed-off-by: Evan Anderson <evan1124@gmail.com>
Suppress String resources build warnings

warnings suppressed are:
aapt: warning: **** string '%s' has no default or required localization for
aapt: warning: string '%s' has no default translation in

Patch Set 2: move ifdef and only suppress warnings for packages that
             define NO_DEFAULT_TRANSLATION_WARNINGS and/or
             NO_LOCALIZATION_WARNING

Patch Set 3: by default do not show warnings unless
             SHOW_DEFAULT_TRANSLATION_WARNINGS and/or
             SHOW_LOCALIZATION_WARNINGS

Change-Id: I50ef2a623959a1cc53053b446328df8e34cc99e8