throw error if public key is not set, yet
add a test for missing public key error
ignore tmp folder needed for tests
use temp module
Merge pull request #27 from joscha/throw-error-if-public-key-not-set

throw error if public key is not set, yet
Merge pull request #30 from joscha/use-temp-module

use temp module
* generateAppId should take param in favor of local state
* add hint to generatePublicKey method about callback parameter