AndroidManifest: Don't match mimeType */* for content: URIs

We don't have a particularly good way of matching email attachments by
extension, since the URI looks something like:

    content://com.android.email.attachmentprovider/2/198/RAW

Setting up the intent-filter to match mimeType */* was causing Easy Token
associations to pop up in the Contacts list.  Limiting this to text/*
and application/* is an imperfect workaround but it makes the problem go
away.

Unfortunately we will still match inappropriate email attachments.
Various MUAs will mark our SDTID files as application/octet-stream,
application/sdtid, text/html, text/xml, or who knows what else.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>