Remove 'scrypt' as a dependency and add instruction te be installed manually. (#22)

README.md

@@ -32,3 +32,8 @@ sudo apt-get install build-essential libssl-dev libffi-dev python-dev
 
 The source tree also contains a tool to create test vectors for the FxA auth
 protocol.
+For that you'll need an additional python package which needs to be installed
+manually:
+```bash
+pip install -r requirements.txt
+```

requirements.txt

@@ -0,0 +1 @@
+scrypt==0.6.1

setup.py

@@ -15,7 +15,6 @@ setup(
                         "requests",
                         "PyBrowserID",
                         "PyHawk",
-                        "scrypt",
                         "six",
                         ],
     packages = ["fxa_client"],