Fix and document small issue around SITE_URL.

README.md

@@ -34,6 +34,15 @@ the site should be available on port 8000 at the IP output by running:
 $ boot2docker ip
 ```
 
+Note that if you're running the site via boot2docker, you'll want to add a
+`.env` file to the project's root director with the IP given by the command
+above. For example, if your IP was `192.168.1.102`, you'd create a `.env` file
+that looked like:
+
+```
+SITE_URL=http://192.168.1.102:8000
+```
+
 For [admin](http://localhost:8000/admin/) access, create admin account with:
 
 ```

docker-compose.yml

@@ -22,5 +22,4 @@ web:
     - DATABASE_URL=mysql://pontoon:asdf@db/pontoon
     - SESSION_COOKIE_SECURE=False
     - HMAC_KEY=asdf
-    - SITE_URL=http://docker:8000
   command: ./bin/run-compose.sh

pontoon/settings/base.py

@@ -43,7 +43,7 @@ def path(*args):
     'hmac-key': os.environ['HMAC_KEY'],
 }
 
-SITE_URL = os.environ['SITE_URL']
+SITE_URL = os.environ.get('SITE_URL', 'http://localhost:8000')
 
 # Microsoft Translator API Key
 MICROSOFT_TRANSLATOR_API_KEY = os.environ.get('MICROSOFT_TRANSLATOR_API_KEY', '')