Updated README with installation hint for people
Added support for short years

There were a few dates that were short years.
Added xlrd requirement
Made munging/ a package
Smarter date parsing in Pandas conversation loading
Merge remote-tracking branch 'upstream/master'

Conflicts:
	munging/ctl_utils.py
Merge remote-tracking branch 'upstream/master'

Conflicts:
	munging/ctl_utils.py