modified error message

After talking with Frantisek and Jakub, I modified his error message. Kind of test to see if I can branch properly!
This message feels way too long. The "consumers" of these messages are either in Apiary web app, some other app or a command line. Messages over 100 characters are difficult to read (it takes time) and are cluttering the CLI or CI interface. 

Also I do not feel that parser should be using this "formal" and "polite". It is important to understand that this parser is also used outside of Apiary (reference to apiary.io support email). Maybe the two use-cases are very different and parser should only provide uniques error / warnings codes with some very basic (sparse) messages that could be reinterpreted in subsequent tooling...