Checks for memory usage ahead of run

[kwhitehall]

@marcuseng and @diegovb, please have a review. This may be needed to drive your mem issues solutions. Note that right now, the min memory required is a raw heuristic calculated by assuming at least two frames of any dataset used will be required in mem simultaneously.
@cgoodale Thoughts?

[diegovb]

I think the code as is will not work with the approach we pivoted to, but we can probably repurpose the code as a way to limit the number of files we process at one time.

[kwhitehall]

@diegovb can you please provide more details on your comment.

[diegovb]

I am not sure of the details right now but once we flesh out the design and start developing we'll probably merge this into our private repos, depending no how the design ends up.