Fixed a bug reported by @tomersimis that happened when fetching Project
contributors thru the getAllProjectContributors method. Closes #62
There was a problem with the way the Json Array was being collected,
switched back to Tomer's approach [1]

Additional work in this commit includes improvement of the User and
Project class within a few methods.

[1]: https://github.com/spgroup/groundhog/blob/master/src/java/main/br/ufpe/cin/groundhog/search/SearchGitHub.java#L637