Contacts mimeType should be specific to the action, not the included data

We incorrectly thought that the MIME Type used in the Contacts actions was
describing the data, but it is really supposed to describe the action.
So we renamed it from openpgp4fpr to encryptfileto in the gpg namespace

refs #1438
when calling gpg2 command-line-style, use "--trust-mode always"

We don't yet have any concept of trust management in the app yet, so set it
to "always" so we can actually encrypt to keys, etc.
move string to XML so it can be translated
handle "Encrypt File To" ContactIntent using the gpg2 command line

This is a first step to getting the full flow working. Right now, its using
the gpg2 tool in a Runtime.exec() call, then just writes out the file next
to the original file to be encrypted.  Ultimately, gpgcli should handle
incoming streams, EXTRA_TEXT, EXTRA_DATA, etc.

refs #1438
"Encrypt File To" sends encrypted file via SEND Intent, i.e. for email, etc

Use the incoming email address to generate an ACTION_SEND Intent, and popup
a chooser so that it is a seamless experience:

1) click "Encrypt File To"
2) select file
3) choose app to send the file with

closes #1438
also refresh key list view after receiving from keyserver, refs #1486