Add test instructions

Author: Greg Bell

README.md

@@ -21,8 +21,16 @@ manually put the resulting file in either `training_data/news` or
 `training_data/sports` dir.
 
 ## Other setup
+`pip install -r requirements.txt`
 Add your feed URLs and email to `feed_classifier.py`
 Configure your email server in `pipeline/mail_sender.py`
 
 ## Running
 Run `feed_classifier.py`, no arguments required.
+
+## Unit tests
+
+```
+pip install -r requirements_dev.txt
+python -m pytest
+```