Crawl data from mutationassessor using Rust

This acts as an illustration for get started with Rust. Also helps Bioinformaticians to crawl mutation data from the site. MutationAssessor offer their APIs for getting data. But keep in minds that the API response is typically slow, so it takes a lot of time for crawling. Check out http://mutationassessor.org/r3/ for more information and its API usage.