Use Scala image since apt fails randomly

.travis.yml

@@ -1,7 +1,7 @@
 dist: trusty
 group: stable
 
-language: ruby
+language: scala
 jdk: oraclejdk8
 
 before_script:
@@ -9,14 +9,6 @@ before_script:
 
 script: /usr/bin/sbt scripted
 
-addons:
-  apt:
-    sources:
-      - sourceline: 'deb https://dl.bintray.com/sbt/debian /'
-      - key_url: 'https://bintray.com/user/downloadSubjectPublicKey?username=sbt'
-    packages:
-      - sbt=1.2.8
-
 # Undo _JAVA_OPTIONS environment variable
 before_script:
   - unset _JAVA_OPTIONS