Improve quoting of varibles in the node shim for -n system

[asottile]

• this isn't quite perfect, for example a node environment containaing a
  single quote character will still produce problems. but this is an
  improvement
• a more thorough approach would be to use shlex.quote -- however I'm not
  100% certain how that would interact with other shells and particularly
  windows

Resolves pre-commit/pre-commit#1483

[ekalinin]

Thanks for the patch, @asottile !

But we have a problem for python 2.7:

AttributeError: 'module' object has no attribute 'quote'

From here: https://travis-ci.org/github/ekalinin/nodeenv/jobs/693637385

Yeah, i know that python 2.7 is EOL, but i believe a lot of people still use it.

[ekalinin]

What about:

try:
    from shlex import quote
except ImportError:
    from pipes import quote

?

[asottile]

oh! yeah I'll just pipes.quotes -- forgot about ye olde python 2 :)