Replace rake-nltk with a customized algorithm

[Demfier]

Currently we are using rake-nltk for extracting important keywords from the error response. It is not efficient because well, the library is trained on human language, not on compiler error messages!

Hence, there is a need for our own implementation of keyword extraction which could do preprocessing of the response we get from hackerearth API and extract important keyword out of it.

This may also require us to declare a Domain Specific Language (DSL) for c0derunR.