adding normalize_groups and downcase_facts options to ec2 dynamic inventory

##### Issue Type:

Feature Pull Request

##### Ansible Version:

ansible 1.8 (devel b4476c238f) last updated 2014/08/14 13:48:46 (GMT -400)

##### Summary:

Add new `downcase_facts` and `normalize_groups` options to EC2 dynamic inventory. 

This is the same change as pull request #7867 but in a clean branch without any merge commits in the branch.