Fix crash on startup on older Android versions (#4).

Author: gianluca-nitti

app/build.gradle

@@ -2,14 +2,14 @@ apply plugin: 'com.android.application'
 
 android {
     compileSdkVersion 25
-    buildToolsVersion "22.0.1"
+    buildToolsVersion "25.0.2"
 
     defaultConfig {
         applicationId "com.github.gianlucanitti.expreval"
         minSdkVersion 15
         targetSdkVersion 25
-        versionCode 2
-        versionName "1.1"
+        versionCode 3
+        versionName "1.2"
     }
     buildTypes {
         release {