Remove types lookup, as it was never used
Remove Visage::Meta types lookup
Make the mock backend return real data:

 - Provide stub data for hosts + metrics
 - Expose the stub data through the hosts + metrics class methods.
 - Generate random data that's graphable
Make all tests pass, except for 95e (for now)
Refactor parse_time out into Visage::Data itself, for maximum reuse