Factor out link builder

services/web/app/coffee/Features/Collaborators/CollaboratorsEmailHandler.coffee

@@ -2,7 +2,16 @@ Project = require("../../models/Project").Project
 EmailHandler = require("../Email/EmailHandler")
 Settings = require "settings-sharelatex"
 
-module.exports =
+
+module.exports = CollaboratorsEmailHandler =
+
+	_buildInviteUrl: (project, invite) ->
+		"#{Settings.siteUrl}/project/#{project._id}/invite/token/#{invite.token}?" + [
+			"project_name=#{encodeURIComponent(project.name)}"
+			"user_first_name=#{encodeURIComponent(project.owner_ref.first_name)}"
+			"r=#{project.owner_ref.referal_id}" # Referal
+			"rs=ci" # referral source = collaborator invite
+		].join("&")
 
 	notifyUserOfProjectShare: (project_id, email, callback)->
 		Project
@@ -36,11 +45,6 @@ module.exports =
 					replyTo: project.owner_ref.email
 					project:
 						name: project.name
-					inviteUrl: "#{Settings.siteUrl}/project/#{project._id}/invite/token/#{invite.token}?" + [
-						"project_name=#{encodeURIComponent(project.name)}"
-						"user_first_name=#{encodeURIComponent(project.owner_ref.first_name)}"
-						"r=#{project.owner_ref.referal_id}" # Referal
-						"rs=ci" # referral source = collaborator invite
-					].join("&")
+					inviteUrl: CollaboratorsEmailHandler._buildInviteUrl(project, invite)
 					owner: project.owner_ref
 				EmailHandler.sendEmail "projectInvite", emailOptions, callback