Adds promotion rule for referred user
Merge branch 'master' into doorbot

Conflicts:
	config/initializers/spree.rb
Adds referred? method to user
adds to_string method for Spree user class
Adds referred orders method to referral model
Adds reffered orders for referral
Adds controller specs, mods referral spec and adds config helpers
Adds promotion spec
Mods admin overrides
Merge branch 'master' into doorbot
Adds rake task to generate referral for users, adds install step gen and adds id to li at header
Merge branch 'master' into doorbot