Adding benefits totals to aggregate table

[jdebacker]

This PR seeks to address issue #119 by adding benefits totals to the aggregate tables.

[jdebacker]

I've also changed labels for the rows of the aggregate table to deal with Issue #117.

[MattHJensen]

@jdebacker, thanks for this PR (and in Tax-Calculator)! Would you mind adding a screenshot of the modified table to a comment?

I am wondering specifically if it looks odd to have revenues and outlays in the same table, and if anything needs to be done visually to separate them. Here is CBO in their January 2020 budget outlook at pg 7:

[jdebacker]

@MattHJensen Here is a screen shot of the updated liabilities table:

[MattHJensen]

Thanks @jdebacker, that seems fine for now. We can always spruce it up later!

@andersonfrailey, this is ready for you to take a look at.

[andersonfrailey]

Everything looks good to me now. Will merge tomorrow afternoon unless there are any new concerns raised.