Changed zipline -> catalyst import paths

* Updated cython build scripts
 * Updated setup.py to to install catalyst package
 * Updated momentum example to use catalyst package
 * catalyst executable now supports loading pipelines from multiple bundles

catalyst/data/session_bars.py

@@ -0,0 +1,36 @@
+# Copyright 2016 Quantopian, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+from abc import abstractproperty
+
+from catalyst.data.bar_reader import BarReader
+
+
+class SessionBarReader(BarReader):
+    """
+    Reader for OHCLV pricing data at a session frequency.
+    """
+    @property
+    def data_frequency(self):
+        return 'session'
+
+    @abstractproperty
+    def sessions(self):
+        """
+        Returns
+        -------
+        sessions : DatetimeIndex
+           All session labels (unionining the range for all assets) which the
+           reader can provide.
+        """
+        pass