Begin work on implementing configuration interface

vcr/__init__.py

@@ -1,6 +1,7 @@
-# Import Cassette to make it available at the top level
-from .cassette import Cassette
+from config import VCR
+
+default_vcr = VCR()
 
 # Also, make a 'load' function available
 def use_cassette(path, **kwargs):
-    return Cassette.load(path, **kwargs)
+    return default_vcr.use_cassette(path, **kwargs)

vcr/config.py

@@ -0,0 +1,9 @@
+from .cassette import Cassette
+
+class VCR(object):
+    def __init__(self, serializer='yaml', cassette_library_dir=None):
+        self.serializer = serializer
+        self.cassette_library_dir = cassette_library_dir
+
+    def use_cassette(self, path, **kwargs):
+        return Cassette.load(path, **kwargs)