Mms: Handle null inputstream from missing file but valid uri.

  - For when you adb restore, an image may corrupt or be missing,
    therefore, we can't always assume that our inputstream from a
    what appears to be a valid file uri won't be null.

Change-Id: I78367c4808fb9967bb750b8713f2cec75805dc05
Merge branch 'cm-11.0' of github.com:CyanogenMod/android_packages_apps_Mms into cm-11.0