Adds margin-fifteen class to custom.css.scss
Adds activation_digest and reset_digest to users.
*Re-seeds DB with new fields
Migration commit #2
Adds new files for mailers, password_reset and 
	activation
New routes for password_resets and
	account_activations
Changes development.rb so mailers can be tested
	in localhost
Changes default time zone to Mountain Time
Changes to user.rb:
*Adds remember_token, activation_token and reset_
	token as attr_accessors in User.
*Adds new methods for activation and pwd reset
*Adds private methods for downcast email and
	creating activation_digest
Adds Sendgrid to production.rb
Changes sessions#create to check if user is 
	activated.
Changes users#create to send activation email 
	instead of automatically signing a user in
Changes condition in current_user method to take
	in two arguments to authenticated?