Update to Apache 2.0 License (jaegertracing#391)

* Update to Apache 2.0 License

Per https://github.com/uber/jaeger/issues/252

* update in actual files

Author: yurishkuro

CHANGELOG.md

@@ -1,6 +1,12 @@
 Changes by Version
 ==================
 
+0.8.0 (unreleased)
+------------------
+
+- Convert to Apache 2.0 License
+
+
 0.7.0 (2017-08-22)
 ------------------
 

CONTRIBUTING.md

@@ -95,30 +95,23 @@ pull request is most likely to be accepted if it:
 ## License
 
 By contributing your code, you agree to license your contribution under the terms
-of the [MIT License](LICENSE).
+of the [Apache License](LICENSE).
 
 If you are adding a new file it should have a header like below.  The easiest
 way to add such header is to run `make fmt`.
 
 ```
 // Copyright (c) 2017 Uber Technologies, Inc.
 //
-// Permission is hereby granted, free of charge, to any person obtaining a copy
-// of this software and associated documentation files (the "Software"), to deal
-// in the Software without restriction, including without limitation the rights
-// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-// copies of the Software, and to permit persons to whom the Software is
-// furnished to do so, subject to the following conditions:
+// 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
 //
-// The above copyright notice and this permission notice shall be included in
-// all copies or substantial portions of the Software.
+// http://www.apache.org/licenses/LICENSE-2.0
 //
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-// THE SOFTWARE.
+// 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.
 ```
-