Fix url in emails, add frontendURL helper (#19)

Fixes #16

spec/fixtures/users.yml

@@ -0,0 +1,11 @@
+# Read about fixtures at http://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
+
+# This model initially had no columns defined. If you add columns to the
+# model remove the '{}' from the fixture names and add the columns immediately
+# below each fixture, per the syntax in the comments below
+#
+one: {}
+# column: value
+#
+two: {}
+# column: value