Move DD code into its own directory (#6)

reference/ddtrace/contrib/mongoengine/__init__.py

@@ -0,0 +1,29 @@
+"""Instrument mongoengine to report MongoDB queries.
+
+``patch_all`` will automatically patch your mongoengine connect method to make it work.
+::
+
+    from ddtrace import Pin, patch
+    import mongoengine
+
+    # If not patched yet, you can patch mongoengine specifically
+    patch(mongoengine=True)
+
+    # At that point, mongoengine is instrumented with the default settings
+    mongoengine.connect('db', alias='default')
+
+    # Use a pin to specify metadata related to this client
+    client = mongoengine.connect('db', alias='master')
+    Pin.override(client, service="mongo-master")
+"""
+
+from ...utils.importlib import require_modules
+
+
+required_modules = ['mongoengine']
+
+with require_modules(required_modules) as missing_modules:
+    if not missing_modules:
+        from .patch import patch, trace_mongoengine
+
+        __all__ = ['patch', 'trace_mongoengine']