MSON Utility functions

Added an MSONUtility file which contains the following functions:

* parseValue
* parseSymbol
* parseTypeName
* parseTypeAttributes
* parse TypeSpecification
* parse TypeDefinition

Also adds `StripMarkdownLink` function to StringUtility file.
No, https://github.com/apiaryio/snowcrash/blob/ab49f40f6db6bb5cb7b5239de674337756d234c4/src/Signature.h#L41