Allow scriptrun to take in file objects as arguments

[zshaheen]

So we can do something like this:

f = open('vcsscript.json', 'r')
cnvs.scriptrun(f)

instead of:

cnvs.scriptrun('vcsscript.json')

It's better for performance when creating a bunch of plots in a loop. This is trivial and requires only changing code around line 614 in vcs/utils.py. I'll hopefully do this soon.