Cleanup requirements.txt so we don't have to maintain separate copies for py2 and py3.

Signed-off-by: Daniel Nephin <dnephin@gmail.com>

compose/utils.py

@@ -97,5 +97,5 @@ def write_out_msg(stream, lines, msg_index, msg, status="done"):
 def json_hash(obj):
     dump = json.dumps(obj, sort_keys=True, separators=(',', ':'))
     h = hashlib.sha256()
-    h.update(dump)
+    h.update(dump.encode('utf8'))
     return h.hexdigest()