Initial Message class
add DateAndTimeExtractor
Throw if not event
Merge branch 'add_date_and_time_extractor'
Use NotAnEventException
Merge branch 'master' of github.com:PennAppsXMIT/parser

Conflicts:
	pipeline.py
Add title (event name) extractor.
-Only supports one event/email
-Extracts the subject
-Uses a regex to remove bracketed terms (i.e. mailing-list titles)
--Fails with nested brackets