BlueprintParser refactor

@zdne Can you review this branch and merge it with `pksunkara/refactor`? I need this to be done in order to check for global duplicate in `ResourceGroupParser.h`.

Also, please check my questions on the diff below. Thanks.
The culprit is the regex of `SYMBOL_IDENTIFIER` in this [line](https://github.com/apiaryio/snowcrash/blob/pksunkara/refactor/src/ResourceGroupParser.h#L18)