Registering MutableStrings, PublicSuffix, CommonCrawl

- [MutableStrings](https://github.com/tanmaykm/MutableStrings.jl) : Provides Mutable ASCII and UTF8 string types that allow modifications to the underlying byte buffer instead of allocating new buffers. Better performance when used in text processing.

- [PublicSuffix](https://github.com/tanmaykm/PublicSuffix.jl) : Julia Interface for working with the Public Suffix List at http://publicsuffix.org/

- [CommonCrawl](https://github.com/tanmaykm/CommonCrawl.jl) : Interface to common crawl dataset on Amazon S3. Can be used to access the crawl database for testing large scale text processing.