Travis build test

-check wether there are default scripts ran by Travis
Apparently images for emulators are not available for all API levels.
Foolowing this
OneBusAway/onebusaway-android#720 (comment)
checking on my local install, it seems API level 25 should be good like that.

.travis.yml

@@ -21,7 +21,7 @@ before_install:
 
 # Emulator Management: Create, Start and Wait
 before_script:
-  - echo no | android create avd --force -n test -t android-26 --abi armeabi-v7a
+  - echo no | android create avd --force -n test -t android-25 --abi armeabi-v7a
   - emulator -avd test -no-audio -no-window &
   - android-wait-for-emulator
   - adb shell input keyevent 82 &
@@ -45,4 +45,4 @@ android:
     - extra-android-m2repository
 
     #tests will be run on this image. More could be added if required
-    - sys-img-armeabi-v7a-android-26
+    - sys-img-armeabi-v7a-android-25