Merge pull request #50 from mark-adams/fix_tests_when_deps_missing

Fixed tests so that they will still run without failure when dependencies (PyCrypto, ecdsa) are missing

Author: jpadilla

jwt/__init__.py

@@ -119,9 +119,6 @@ def prepare_RS_key(key):
 
 try:
     import ecdsa
-    from Crypto.Hash import SHA256
-    from Crypto.Hash import SHA384
-    from Crypto.Hash import SHA512
 
     signing_methods.update({
         'ES256': lambda msg, key: key.sign(msg, hashfunc=hashlib.sha256, sigencode=ecdsa.util.sigencode_der),