Refactor SMI collector to use client-go.

[Tatsinnit]

Following workitem is associated with #124 in a sense that both the collectors extensively used the kubectl implementation which we should plan of converting into golang -> pkg based implementations which could involve using kubernetes - client-go or kubernetes or apiextensionsClient under the hood.

The long term benefit we are aiming for is the test-ability (Increase codeCoverage), along with removal of kubectl binary download, if we 100% move to using the pkgs, (which is medium to long term plan)

some helpful pkgs:

• https://github.com/kubernetes/client-go
• https://github.com/kubernetes/apiextensions-apiserver

Thanks heaps, fyi: @SanyaKochhar , thanks and I could collaborate with you, for help.

cc: @rzhang628 , @arnaud-tincelin , @qpetraroia