Updater: Fix Android Studio build

Increase the min API level to support notification channels
without compat libraries.

Change-Id: Ia2f383a108dbb4fc38b3d923ac7c5e3d173fcf71

build.gradle

@@ -10,7 +10,7 @@ buildscript {
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.0.1'
+        classpath 'com.android.tools.build:gradle:3.1.0'
     }
 }
 
@@ -25,7 +25,7 @@ android {
     buildToolsVersion '27.0.3'
 
     defaultConfig {
-        minSdkVersion 24
+        minSdkVersion 26
         targetSdkVersion 27
     }
 
@@ -61,7 +61,7 @@ android {
 dependencies {
     compileOnly fileTree(dir: 'system_libs/', include: ['*.jar'])
 
-    def supportLibVersion = "27.0.2"
+    def supportLibVersion = "27.1.0"
     implementation "com.android.support:appcompat-v7:${supportLibVersion}"
     implementation "com.android.support:cardview-v7:${supportLibVersion}"
     implementation "com.android.support:design:${supportLibVersion}"