Fix signature check scoping issue.

Signature checks were failing, in the binary-document case of
openpgp_packet_signature.verify() the variable i was being referenced
when there was no i in scope; instead it was getting 8 from a global
variable i, and trimming 8 bytes off the beginning of the data.

The global i was being set by the CAST5 cipher -- this also fixes
that to be a local variable.

Also add unit test to confirm.
fix array index in verify() with multiple pubkeys.

The log message was showing the Ith userId of the Ith pubkey,
which may not exist. All other code paths use the 0th userid
of the Ith pubkey, do that too.
Add support for GnuPG type 1001 s2k extension

This is a Gnu extension for private keys with stripped secrets, which
can be created by GnuPG's --export-secret-subkeys mode.

Before this patch, "ERROR:  unknown s2k type! 101" would be logged as an
error (though other than that, things seemed to function normally).
openpgp_keyring include subkeys by ID

openpgp_keyring.getPublicKeysForKeyId will now search subkeys
when looking for the ID, and return a key object based on that
subkey.

Updated to add a method, getSubKeyAsKey, to openpgp_msg_publickey.
This returns a full-fledged openpgp_msg_publickey object for a
chosen subkey.
minimize.sh make file ordering deterministic

Do find | sort | cat instead of find -exec cat when building
resources/openpgp.js. The order of files returned by find isn't
deterministic, which could lead to spurious differences.
Merge pull request #63 from brianbloniarz/master

Several bugfixes involving GnuPG interop