TST: Make network decorator impose a skipTest catching URLErrors

[jtratner]

Basically, do this in the network decorator:

    @wraps
    def network_wrapper(*args, **kwargs):
        try:
            return t(*args, **kwargs)
        except URLError:
            raise nose.skipTest

Working on it right now

[cpcloud]

@jtratner b4 u spend time on this maybe see pydata#3822

[jtratner]

@cpcloud yeah, but it really needs to be opt-out rather than opt-in

[jreback]

@cpcloud close this? (as @jtratner put all of the stuff in)

[cpcloud]

this will be closed by #3914

[jreback]

great