MmsProvider throws an exception on unknown column

If the vcard importer is handed a uri to an MMS part, it will crash.
The MmsProvider will throw an exception when it queries for a column
name not in the schema. With this change, the MmsProvider will simply
return a null cursor when queried for an unkonwn column.

Change-Id: I967f4a631d24eb5a43a70d563c2008f555d0aa3c
1 file changed