Merge branch 'master' into bens-cleaned-up-py3

INSTALL.md

 * install PostgreSQL 8.3+
 
+* install Rabbit MQ
+  This is needed for celery to work, which does background processing such as
+  the processing of uploaded list-of-voter CSV files.  
+
 * make sure you have virtualenv installed:
 http://www.virtualenv.org/en/latest/