Add contributor, 2.7.0 release notes

Author: Luke Bakken

README.md

@@ -142,6 +142,7 @@ Contributors
 * Soren Hansen
 * Sreejith Kesavan
 * Timothée Peignier
+* [`tobixx`](https://github.com/tobixx)
 * [Tin Tvrtković](https://github.com/Tinche)
 * [Vitaly Shestovskiy](https://github.com/lamp0chka)
 * William Kral

RELNOTES.md

@@ -1,5 +1,9 @@
 # Riak Python Client Release Notes
 
+## [`2.7.0` Release](https://github.com/basho/riak-python-client/issues?q=milestone%3Ariak-python-client-2.7.0)
+ * Riak TS 1.5 support
+ * Support for `head` parameter
+
 ## [`2.6.1` Release](https://github.com/basho/riak-python-client/issues?q=milestone%3Ariak-python-client-2.6.0)
  * NOTE: Due to pypi upload errors, `2.6.1` takes the place of `2.6.0`.