Switch to Scala 2.12.7 (#91)

diff --git a/.travis.yml b/.travis.yml
index f80e115..a5036d5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,7 +3,7 @@
 language: scala
 
 scala:
-  - 2.11.6
+  - 2.12.7
 
 services:
   - docker
diff --git a/settings.gradle b/settings.gradle
index e422fa2..22158d2 100644
--- a/settings.gradle
+++ b/settings.gradle
@@ -7,6 +7,6 @@
 ]
 
 gradle.ext.scala = [
-    version: '2.11.8',
+    version: '2.12.7',
     compileFlags: ['-feature', '-unchecked', '-deprecation', '-Xfatal-warnings', '-Ywarn-unused-import']
 ]