Upgrade build tools (25) and gradle plugin (2.2.2)

Also, Java SDK 8 is now required by dependency.

.travis.yml

@@ -3,8 +3,11 @@ android:
   components:
     - platform-tools
     - tools
-    - build-tools-23.0.3
+    - build-tools-25.0.0
     - extra-google-m2repository
     - extra-android-m2repository
     - android-23
     - sys-img-x86-android-18
+jdk:
+  # - openjdk8 # not yet available
+  - oraclejdk8

README.md

@@ -20,8 +20,9 @@ Initially started by the Wikimedia Foundation, this app is now maintained by vol
 
 ### Requirements ###
 
-1. [Android SDK][3] (Level 23)
-2. [Gradle][4]
+1. Java SDK 8 (OpenJDK 8 or Oracle Java SE 8)
+2. [Android SDK][3] (Level 23)
+3. [Gradle][4]
 
 ### Build Instructions ###
 

app/build.gradle

@@ -11,9 +11,9 @@ dependencies {
     compile 'ch.acra:acra:4.7.0'
     compile 'org.mediawiki:api:1.3'
     compile 'commons-codec:commons-codec:1.10'
-    compile 'com.android.support:support-v4:23.4.0'
-    compile 'com.android.support:appcompat-v7:23.4.0'
-    compile 'com.android.support:design:23.4.0'
+    compile 'com.android.support:support-v4:25.0.0'
+    compile 'com.android.support:appcompat-v7:25.0.0'
+    compile 'com.android.support:design:25.0.0'
 
     testCompile 'junit:junit:4.12'
 
@@ -23,7 +23,7 @@ dependencies {
 
 android {
     compileSdkVersion 23
-    buildToolsVersion "23.0.3"
+    buildToolsVersion "25.0.0"
 
     useLibrary  'org.apache.http.legacy'
 

build.gradle

@@ -5,7 +5,7 @@ buildscript {
         mavenCentral()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:2.1.3'
+        classpath 'com.android.tools.build:gradle:2.2.0'
     }
 }