HONEYCOMB-46: Add NSH feature in Honeycomb

HONEYCOMB-46: Add NSH feature in Honeycomb

PatchSet 14: Refactor NSH Plugin based on new code organization
PatchSet 13: merge Change 1796: Add nsh-entry Yang Model
PatchSet 12:augment with vxlan-encap-type
PatchSet 11: rebase and make nsh yang model visible to ODL netconf
PatchSet 8: move vpp-nsh.yang to v3po/nsh folder
PatchSet 7: split two patches: nsh-entry and nsh-map
PatchSet 6: support md-type1 and md-type2
PatchSet 5: Use encap-type and parameters
PatchSet 4: Use identity instead of enum
PatchSet 3: consolidate comments from Ed
PatchSet 2: fix indent issue.

Change-Id: I18353b714d39199ffa346fd39da6cafdbcc1b30c
Signed-off-by: Hongjun Ni <[email protected]>
Signed-off-by: Ed Warnicke <[email protected]>