Modify TAPI 2.0 to avoid yang-tool limitation

Change-Id: Ic512f3aa761548a2b45457543e6b23a392500902
diff --git a/models/tapi/src/main/yang/tapi-common@2017-05-31.yang b/models/tapi/src/main/yang/tapi-common@2017-05-31.yang
index b52896e..eb3ce4f 100644
--- a/models/tapi/src/main/yang/tapi-common@2017-05-31.yang
+++ b/models/tapi/src/main/yang/tapi-common@2017-05-31.yang
@@ -82,10 +82,10 @@
         }

         container context {

         	presence "TAPI";

-            uses context;

+            uses _context;

             description "none";

         }

-        grouping context {

+        grouping _context {

             list service-interface-point {

                 key 'uuid';

                 min-elements 2;