Suggestion: Budget Enhancements

[bchang02]

I forked this project a while ago mainly because I wanted to add some functionality to the Budget module on the Overview page, but didn't have the time. These include:

1. Add sorting capability to category and percentage
2. Combining categories (addresses https://mint.lc.intuit.com/questions/1034188)
3. Excluding a category from being factored in the Total bar (eg. categories such as Rent is usually a monthly transaction which skews the total "progress" bar)

I don't have much experience developing Chrome extensions, but would like to start. When I have time, I can work on this and submit a pull request if no one picks this up.