[FEA] add ability to print shape only

[luitjens]

When we get to larger tensors it is useful to print shapes for debugging without printing the contents. We should add this functionality.

Options I see:

1. printShape(op)
2. print(op, false) // changes signature of print to print(T op, content=true)

[tylera-nvidia]

all we should need to do is move this blurb to a separate API , and make it conditional in the print call