build: update tools, fix travis version, compile with 26

.travis.yml

@@ -7,7 +7,7 @@ android:
     - platform-tools
     - tools
     - extra-android-m2repository
-    - build-tools-25.0.2
-    - android-25
+    - build-tools-26.0.2
+    - android-26
 
 script: cd Clover && ./gradlew build --console plain -x lint

Clover/app/build.gradle

@@ -13,7 +13,7 @@ def getCommitHash = { ->
 }
 
 android {
-    compileSdkVersion 25
+    compileSdkVersion 26
     // update the travis config when changing this
     buildToolsVersion '26.0.2'
 

Clover/build.gradle

@@ -5,7 +5,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.0.0'
+        classpath 'com.android.tools.build:gradle:3.0.1'
     }
 }