Merge pull request #4695 from mitchellh/readmeproviders

update readme with supported providers

README.md

@@ -27,14 +27,19 @@ comes out of the box with support for the following platforms:
 
 * Amazon EC2 (AMI). Both EBS-backed and instance-store AMIs
 * Azure
+* CloudStack
 * DigitalOcean
 * Docker
 * Google Compute Engine
+* Hyper-V
+* 1&1
 * OpenStack
 * Parallels
+* ProfitBricks
 * QEMU. Both KVM and Xen images.
-* VirtualBox
+* Triton (Joyent Public Cloud)
 * VMware
+* VirtualBox
 
 Support for other platforms can be added via plugins.