[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.
Okay, so the "issue" is that these regular expressions shouldn't be global variables on the patient object. I'm putting "issue" in quotes, because I imagine this method works, but it's not very principled—think about a multi-threaded example. That being said, this is Rails, not Java. I'm going to merge, but we should remember to refactor this at some point.