Fixed ASCII armor decoding bug

Sometimes, there's a blank line between the encoded message body and the checksum line at the end. In those cases, decryption used to crash. Changed only openpgp_encoding_deArmor() in openpgp.encoding.asciiarmor.js to make it resilient to this case.

Cleaned up copy+pasted code in the same function. No other changes.
Merge pull request #105 from dcposch/master

Fixed ASCII armor decoding bug