Feature: capturing execution logs

[dgkf]

Going over the report, one feature that is lacking if we wanted to pass a package object as a parameter would be execution logs.

We store some logs (I think currently only for installation), but we may want to capture a few others for key deliverables like R CMD check and coverage.

This was one feature that was quite problematic for riskmetric, often producing a lingering output device that would eat console output if execution was interrupted. If we wanted to go down this path, I'd like to plan way to capture output that is less flaky.