bonding options rework experiment (dcbw/bondopts)

[Dan Williams <dcbw redhat com>]

Hi,

I've pushed my experiments here to dcbw/bondopts, enough that it
compiles and passes 'make check' in libnm-util, although we certainly
don't have enough testcase coverage of bonding to make sure it works.

My main attempts were to use the normal GObject property ParamSpecs for
min/max validation and all defaults, and to reduce some of the legacy
property complexity by just exposing all the properties in the old
'options' property.

Thoughts?

Dan