Added new InstaPage and Hashtag classes
* Hashtag class wraps the data from a scraped Instagram hashtag
* InstaPage is an abstract class representing any scrapable Instagram page; InstaUser and Hashtag are subclasses
Added new methods to InstaClient
* scrape() can be used to scrape an Instagram page
* get_user() and get_hashtag() scrape a profile or hashtag
* get_username retrieves username from a userid
Updated docs, docstrings, variables and method names to reflect the changes
* Notable change is that user_map is now page_map
**Full Changelog**: https://github.com/TDKorn/insta-tweet/compare/v2.1.3...v2.2.0