first pass at Mailer.list - #20
provide a block to Mailer.list to generate item markup
make all test mailers available in preview
put all stats in single table - closes #38
add a test mailer that includes all section types
left-align text in list items
add test for Metric#total
change the list to expect a date range
Merge remote-tracking branch 'upstream/master' into list

Conflicts:
	lib/tricle/group.rb
	lib/tricle/metric.rb
	lib/tricle/report.rb
	lib/tricle/templates/email.html.erb
	spec/app/group_test_mailer.rb
	spec/presenters/metric_spec.rb
	spec/unit/report_spec.rb
Merge pull request #41 from afeld/list

@fancyremarker => List support