Ondemand pricing for Resource Groups + Weekly Email Service

Ondemand Pricing:
- This feature is disabled by default.
- Uses the ondemand pricing instead of the reservation prices when calculating the costs of Resource Groups
- It can be enabled by adding the following property to ice.properties: "ice.resourceGroupPricing=ondemand"
- Using ondemand prices allows teams that aren't using any reserved instances to still make use of the Resource Groups breakdown page and custom tags to see how much they are actually spending.

Weekly Email Service:
- Added flag in ice.properties to enable the weekly email service
- Modified the bootstrap.groovy to instantiate the service