get file extension associations working on more apps

Based on the comment in OpenPGP Keychain's AndroidManifest.xml:

  Do _not_ set mimeType for .gpg! Cyanogenmod's file manager will only show
  Keychain for .gpg files if no mimeType is set! For OI Filemanager it makes
  no difference, .gpg files can't be associated.

I ended up making entirely duplicate sections, one with a mimeType and the
other without.  This does seem to fix things on OI File Manager and ASTRO. I
wonder what it is going to break...

refs #1646, #1455
show Toast on failure to get the full GnuPGKey

A bad or corrupt key will cause GnuPG to barf, so catch it and warn the
user.  A partial download from a keyserver is one such example.

fixes #3052
handle importing large keys from the keyserver

Originally, it was just putting the whole text from the keyserver into the
Intent's EXTRA_TEXT.  This was rapidly running into size limits, and
throwing strange exceptions like:

"FAILED BINDER TRANSACTION!" android.os.TransactionTooLargeException

fixes #3046
remove wizard from history after it completes

Once the user has chosen from the last button set in the wizard, it should
finish and never return!
handle empty keyserver lists

Forgot to handle the case where newData exists but has no items...
recreate KeyListContactsAdapters after sync completes

It seems that the ListFragments won't update unless they get an entirely
new adapter, so don't check if the current one exist.  Instead just always
create a new one.

fixes #2961
add null guard when handling Intents from Contacts

A ContentResolver.query() can return null, so we should check for that.

fixes #1697