fix JSON.parse(null)

if window.localStorage.config is null then JSON.parse returns an error about "u" not being valid (the word "undefined" is not valid JSON apparently :). So I test for null-ness first.
API accepts single public key string instead of array
include other key arrays
use .length to test
bump version to dev
Merge pull request #229 from cdwiegand/master

fix JSON.parse(null)
update function documentation
Update README.md to add decryption example

Update README.md to add decryption example
Merge pull request #232 from msjoinder/single_public_key

API accepts a single public key or an array
Merge pull request #237 from alessioalex/master

Update README.md to add decryption example
Update README.md
bump version
bump version
Throw an error if a wrong public key is used to verify a signature.
bump version for dev
Allow removal of passphrase protection by calling encrypt with an empty passphrase
Warn user with signature null for wrong public key instead of exception.
Merge pull request #238 from openpgpjs/no-passphrase

No passphrase
new release
bump version