Add ECS 1.2.0 fields.ecs.yml (elastic#14052)

* Add ECS 1.2.0 fields.ecs.yml

This adds the fields.ecs.yml data from ECS 1.2.0.

Libbeat's duplicate definition of error.type was removed.

* Update github.com/elastic/ecs in vendor to 1.2.0

* make notice

NOTICE.txt

@@ -907,13 +907,28 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 SOFTWARE.
 --------------------------------------------------------------------
 Dependency: github.com/elastic/ecs
-Version: v1.1.0
-Revision: cc1d96bf3f70a8e6af1e436a0283ef22b6af3dd2
+Version: v1.2.0
+Revision: 2eaac192a1ca67edab727d7d9d526c5142ae3eb5
 License type (autodetected): Apache-2.0
 ./vendor/github.com/elastic/ecs/LICENSE.txt:
 --------------------------------------------------------------------
 Apache License 2.0
 
+-------NOTICE.txt-----
+Elastic Common Schema
+Copyright 2018 Elasticsearch B.V.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
 
 --------------------------------------------------------------------
 Dependency: github.com/elastic/go-libaudit