Find package.json, parse it, and check deps

Adding code to grab current project's package.json file, read it in, and check the dependencies.

@kenwheeler and @rgbkrk, I have added some code to grab the project's `package.json` file (I just hacked this, there is probably a better approach) and then it reads in the `package.json` if it exists (again, probably cleaner way to do this), and then I run our existing functions on this to check what deps need to be updated. I don't necessarily intend for this to be merged as is, but rather wanted to start a discussion about how we should tackle this portion of the code. Thoughts?

Next step is to start highlighting deps in the editor when `package.json` is opened.