Support receiving shared plain text

This will parse the shared text, and add an item for each line
in that text.

This works very well with (for example) the shopping-list feature
of the MyCookbook app.
I think this also fixes the feature request found here:
http://openintents.uservoice.com/forums/86421-general/suggestions/1294309-oi-shopping-list-sms-email-copypaste-import-expor