Remove use of eval in favor of first class function

[zrnsm]

There seems to be an unnecessary use of eval for timestamp aggregation. This patch uses the sum function directly. The other changes are just removal of unnecessary trailing whitespace.

[akejariwal]

@caniszczyk Can you please merge this. I approve the merge.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}