Add support for the c3 family in the instance types parser
Update pricing parser and API to handle new data sources

The old pricing-on-demand-instances.json has been replaced by a file per OS. To support this the whole handling of downloading and merging the pricing data had to change, but at the same time support for RHEL and SLES is added.

Now an instance type will be included if it has a price, not only if it has data.
Remove instances without on-demand-price from the UI
Sort C3 after C1 and G2 after M2 in the UI
Add RHEL and SLES to the UI
Show tooltip next to SSD disks