Adding rackspace to the list

README.md

@@ -265,6 +265,7 @@ Table of Contents
   * https://cloud.google.com/compute/ - Google Compute Engine gives $300 over 60 days
   * https://cloud.google.com/container-engine/ - Google Container Engine for run Docker containers(Alpha). Pricing: same of Google Compute Engine.
   * https://nsone.net/ - Data Driven DNS, automatic traffic management, 1M free Queries
+  * https://developer.rackspace.com/signup/ - Get $50/month for 12 months to use toward cloud services.
 
 ## DBaaS
    * https://mongolab.com/ - MongoDB as a service (500mb free)