Tests for wallet encryption stuff

Added a functional test which tests the encryptwallet, walletpassphrase, walletpassphrasechange, and walletlock RPCs

test/functional/test_runner.py

@@ -111,6 +111,7 @@ BASE_SCRIPTS= [
     'rpcnamedargs.py',
     'listsinceblock.py',
     'p2p-leaktests.py',
+    'wallet-encryption.py',
 ]
 
 EXTENDED_SCRIPTS = [