Upgraded to 3.1

git-svn-id: https://silverstripe-ecommerce.googlecode.com/svn/modules/ecommerce_newsletter/trunk@4623 950b781c-c544-efab-2f99-90083ee69683
Updating composer.json files to correct reference to e-commerce

git-svn-id: https://silverstripe-ecommerce.googlecode.com/svn/modules/ecommerce_newsletter/trunk@4656 950b781c-c544-efab-2f99-90083ee69683
Adding and updating README files

git-svn-id: https://silverstripe-ecommerce.googlecode.com/svn/modules/ecommerce_newsletter/trunk@4688 950b781c-c544-efab-2f99-90083ee69683