Add "ecb" crypto mode support.
OCD
Fix a bug, we should default to "cbc" IF mode is nil.
Merge branch 'master' of github.com:Shopify/dukpt into feature/ecb-mode

Conflicts:
	lib/dukpt/encryption.rb
Clean up.
Merge.
Fix issue during merge.
Clean up this, again.
Add a test for the crypto mode.
Clean up define.
Merge pull request #6 from Shopify/feature/ecb-mode

Add "ecb" crypto mode support.