Add built tools 19.1.0 to .travis.yml

Author: minbi

.travis.yml

@@ -5,6 +5,7 @@ android:
     - tools # see https://github.com/travis-ci/travis-ci/issues/6040#issuecomment-219367943)
     - platform-tools
     - build-tools-24.0.2
+    - build-tools-19.1.0
     - android-11
 sudo: true
 script:
@@ -13,4 +14,4 @@ script:
     - mvn clean install -Dmaven.javadoc.skip=true cobertura:cobertura
 
 after_success:
-  - bash <(curl -s https://codecov.io/bash)
+  - bash <(curl -s https://codecov.io/bash)