NETCONF server data model

Summary: Added yang specs and the pyang plugin for generating the new NETCONF server data model. Autotools is not configured for checking pyang yet.

Test Plan: try to compile mand (the new pyang plugin is automatically used in the Makefile)

Reviewers: aschultz

CC: mkraemer, druss

Maniphest Tasks: T400, T356, T355

Differential Revision: https://review.tpip.net/D1236
NETCONF server data model

Summary: Added yang specs and the pyang plugin for generating the new NETCONF server data model. Autotools is not configured for checking pyang yet.

Test Plan: try to compile mand (the new pyang plugin is automatically used in the Makefile)

Reviewers: aschultz

Reviewed By: aschultz

CC: mkraemer, druss

Maniphest Tasks: T400, T356, T355

Differential Revision: https://review.tpip.net/D1236