Add autotest guide

Developer-Guide--Autotester-Technical-Tour.md

@@ -0,0 +1,32 @@
+# Developer Guide: A technical tour through the autotester
+
+The autotester is a program designed to automatically run student assignments against preconfigured test files.
+
+## Python Autotester
+
+![Autotest Diagram](images/autotest_diagram.png)
+
+The autotester has three major components:
+
+1. Client - Flask API Client
+2. Server - Python Server
+3. Cache - Redis Cache
+
+The python autotester has two testers to choose from:
+
+1. Pytest - Third party PyPy project
+2. Unittest - Builtin testing framework
+
+### Test Creation
+
+1. Markus
+  i. The  `update_test_specs` [function](https://github.com/MarkUsProject/Markus/blob/master/app/controllers/api/assignments_controller.rb#L199) updates several local records with the information provided.
+  ii. The `AutotestSpecsJob` which calls the `automated_tests_helper.update_settings` function
+  iii. The `update_settings` obtains all the settings information and makes a call to the Autotester Client api, to either update the settings or create a new settings record
+2. Autotest Client
+  i. The autotest client on a new test creation, will have it's `/settings` [endpoint](https://github.com/MarkUsProject/markus-autotesting/blob/master/client/autotest_client/__init__.py#L213) called which does 2 things. 1. Incremement the `autotest:settings_id` and 2. save the settings provided from MarkUs onto the redis cache as `autotest:settings`
+
+### Test Execution
+
+1. Markus
+  i. When a test is scheduled, a resque