Added EmbeddedDocumentListField Implementation

- Added new field type: EmbeddedDocumentListField.
- Provides additional query ability for lists of embedded documents.
- Closes MongoEngine/mongoengine#503.

docs/apireference.rst

@@ -79,6 +79,7 @@ Fields
 .. autoclass:: mongoengine.fields.GenericEmbeddedDocumentField
 .. autoclass:: mongoengine.fields.DynamicField
 .. autoclass:: mongoengine.fields.ListField
+.. autoclass:: mongoengine.fields.EmbeddedDocumentListField
 .. autoclass:: mongoengine.fields.SortedListField
 .. autoclass:: mongoengine.fields.DictField
 .. autoclass:: mongoengine.fields.MapField
@@ -103,6 +104,21 @@ Fields
 .. autoclass:: mongoengine.fields.ImageGridFsProxy
 .. autoclass:: mongoengine.fields.ImproperlyConfigured
 
+Embedded Document Querying
+==========================
+
+.. versionadded:: 0.9
+
+Additional queries for Embedded Documents are available when using the
+:class:`~mongoengine.EmbeddedDocumentListField` to store a list of embedded
+documents.
+
+A list of embedded documents is returned as a special list with the
+following methods:
+
+.. autoclass:: mongoengine.base.datastructures.EmbeddedDocumentList
+    :members:
+
 Misc
 ====