release: Bump to version 0.3.1 and add env var to readme (#14)

Author: jgwerner

README.md

@@ -40,6 +40,14 @@ This package leverages the same Python API available with `nbgrader`. Therefore
 nbgrader autograde "<assignment-name>"
 ```
 
+### Toggle to use the standard syncronous autograder
+
+This package includes the option to set an environment variable to toggle whether to use the `asyncronous` version of the autograder or the `syncrononous` version (default is `async`):
+
+| Environment Variable | Description | Default |
+| --- | --- | --- |
+| NBGRADER_ASYNC_MODE | Used to set whether the autograder runs syncronous or asyncronous mode | "true"  |
+
 ## Export Grades as a CSV
 
 Follow the steps below to export grades from the `nbgrader` database to a `*.csv` (default is `canvas_grades.csv`) file:

async_nbgrader/_version.py

@@ -1,2 +1,2 @@
-version_info = (0, 2, 0)
+version_info = (0, 3, 1)
 __version__ = ".".join(map(str, version_info))