Started ResourceGroupParser refactor

Conflicts:
	src/ResourceGroupParser.h
Finished ResourceGroupParser logic
Refactored ResourceGroupParser tests
Fixed the tests in ResourceGroupParser
Check for resource global duplicate
Started with BlueprintParser refactor
Finished BlueprintParser refactor
Tests refactor for BlueprintParser done
Resources can be nested in Blueprint
Allow support for blueprint starting with resource or resource group
Finalized BlueprintParser refactor
Merge pull request #139 from apiaryio/pksunkara/blueprint-parser

BlueprintParser refactor
Merge pull request #133 from apiaryio/pksunkara/refactor

ResourceGroupParser refactor