Add ktlintFormat Gradle task.

build.gradle

@@ -194,6 +194,13 @@ tasks.register('ktlint', JavaExec) {
     args "app/src/**/*.kt", "!**/build/**/*.kt"
 }
 
+task ktlintFormat(type: JavaExec, group: "formatting") {
+    description = "Fix Kotlin code style deviations."
+    classpath = configurations.ktlint
+    main = "com.pinterest.ktlint.Main"
+    args "-F", "app/src/**/*.kt", "!**/build/**/*.kt"
+}
+
 tasks.withType(io.gitlab.arturbosch.detekt.Detekt.class).configureEach {
     exclude("**/resources/**")
     exclude("**/tmp/**")