[In Progress] Scraping, Reference Ranges and Units

This is a pull request in progress. This PR includes work for practice and provider scraping (fixes #87), reference ranges (fixes #53) and units(fixes #82). I was almost done with scraping, but I decided to put more effort to scrape all the information I can find online. 

For reference ranges and units, there is more work to do. I have designed what I will be doing for units. For reference ranges, I will work on the front end and connecting reference ranges to record update values.
It will be our version of [strftime](http://apidock.com/ruby/DateTime/strftime). I'd start with something as simple as `"%v %u (%r)"` and slowly increase complexity from there. Edge cases that we'd eventually have to represent:
* Values with multiple words
* Units with multiple words
* You've already dealt with these, but ranges with inequalities