include copy of django_extension, dont install django from git

contrib/django_extensions/docs/sqldiff.rst

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+sqldiff
+=======
+
+:synopsis: Prints the ALTER TABLE statemens for the given appnames.
+
+Django command that scans all models for the given appnames and compares
+their database schema with the real database tables.
+
+It indicates how columns in the database are different from the SQL that would
+be generated by Django. This command is not a database migration tool. Though
+it might certainly be of help during migrations. It's purpose is to show the
+current differences as a way to checking or debugging your models compared to
+the real database tables and columns.
+
+Supported Databases
+-------------------
+
+Currently the following databases are supported:
+
+* PostgreSQL
+* Sqlite3
+* MySQL
+* Oracle
+
+Patches to support other databases are welcome ! :-)
+
+
+Example Usage
+-------------
+
+::
+
+  # View SQL differences for all installed application
+  $ ./manage.py sqldiff -a
+
+::
+
+  # View SQL differences for all installed application using text instead of SQL
+  $ ./manage.py sqldiff -a -t