Added pull request template.
Added pull request template.

Making following assumptions:
* Pull requests do not need to originate from Issues discussion.
	* But encouraged
* No current CONTRIBUTING.md file
	* honor code that people follow current coding conventions
* Tests run and passed
	* New features require additonal tests for confirmation

oroszgy/spaCy.hu,aikramer2/spaCy,explosion/spaCy,Gregory-Howard/spaCy,banglakit/spaCy,banglakit/spaCy,recognai/spaCy,spacy-io/spaCy,aikramer2/spaCy,Gregory-Howard/spaCy,Gregory-Howard/spaCy,raphael0202/spaCy,banglakit/spaCy,Gregory-Howard/spaCy,Gregory-Howard/spaCy,raphael0202/spaCy,oroszgy/spaCy.hu,honnibal/spaCy,oroszgy/spaCy.hu,raphael0202/spaCy,aikramer2/spaCy,oroszgy/spaCy.hu,explosion/spaCy,raphael0202/spaCy,honnibal/spaCy,honnibal/spaCy,banglakit/spaCy,recognai/spaCy,recognai/spaCy,aikramer2/spaCy,raphael0202/spaCy,explosion/spaCy,oroszgy/spaCy.hu,explosion/spaCy,banglakit/spaCy,explosion/spaCy,recognai/spaCy,recognai/spaCy,oroszgy/spaCy.hu,spacy-io/spaCy,spacy-io/spaCy,spacy-io/spaCy,spacy-io/spaCy,banglakit/spaCy,aikramer2/spaCy,aikramer2/spaCy,explosion/spaCy,Gregory-Howard/spaCy,raphael0202/spaCy,honnibal/spaCy,recognai/spaCy,spacy-io/spaCy