Added support for using on demand prices when calculating usage costs for Resource Groups
Added option in ice.properties to choose between ondemand or reserve pricing when calculating Resource Group costs
Added implementation of Weekly Cost Emails
Update README.md
Changed ice option to use modeled costs for resource groups to ice.resourceGroupCost following code review
Merge pull request #54 from oliviervg1/master

Ondemand pricing for Resource Groups + Weekly Email Service
Merge pull request #56 from ma78/patch-1

Update README.md