Add support for Origin.

[mike-albano]

Add support, via flag, for the gNMI Origin in gnmi_set. This will disambiguate the namespace when a vendor utilizes both OpenConfig and rfc7951 (or otherwise vendor-specific) YANG modules.

When sending OpenConfig JSON, the origin key will have a value of "openconfig".

[larryleguo]

we are working on a new version of gnmi server, which will cover this feature. If there is an immediate need for it, we can have an update based on the current version.

[samribeiro]

I think albano specifically mentioned the client gnmi_set to support this.

[larryleguo]

Got it.

[mike-albano]

Sorry, missed this in my inbox. Sam is correct; I was referencing the client in this Issue. Thanks for the work, looking forward to the new version!

[phani2410]

Hi, I have added a pull request to solve this particular issue.
Travis is not able to build the code for go 1.8 version for the reason unknown.

Please check this request.

#38

[idefixcert]

we are working on a new version of gnmi server, which will cover this feature. If there is an immediate need for it, we can have an update based on the current version.

@larryleguo
I this already the new version of gnmi server? Or is a new one planned?