Update buildToolsVersion to 26.0.1, supportLibrary and SdkVersion to 26. Closes #848 (#849)

Author: annalabellarte

.travis.yml

@@ -21,7 +21,7 @@ android:
     - tools
 before_script:
   - mv library/google-services.json app/google-services.json
-  - ${ANDROID_HOME}tools/bin/sdkmanager --channel=3 "tools" "platform-tools" "build-tools;25.0.3" "platforms;android-25" "extras;google;m2repository"
+  - ${ANDROID_HOME}tools/bin/sdkmanager --channel=3 "tools" "platform-tools" "build-tools;26.0.1" "platforms;android-26" "extras;google;m2repository"
 script: ./gradlew clean assembleDebug check
 after_failure:
   # tests

constants.gradle

@@ -4,12 +4,12 @@ project.ext {
     version = '2.2.0'
     pomdesc = 'Firebase UI Android'
 
-    compileSdk = 25
-    targetSdk = 25
+    compileSdk = 26
+    targetSdk = 26
     minSdk = 14
 
-    buildTools = '25.0.3' // Remember to also update in .travis.yml
+    buildTools = '26.0.1' // Remember to also update in .travis.yml
 
     firebaseVersion = '11.0.4'
-    supportLibraryVersion = '25.4.0'
+    supportLibraryVersion = '26.0.0'
 }