Add .gitignore file to exclude Android Studio configs

.gitignore

@@ -1,20 +1,7 @@
+.idea/
 *.iml
-.gradle
-/local.properties
-/.idea/caches
-/.idea/libraries
-/.idea/modules.xml
-/.idea/workspace.xml
-/.idea/navEditor.xml
-/.idea/assetWizardSettings.xml
-.DS_Store
-/build
-/captures
-.externalNativeBuild
-.cxx
+build/
 local.properties
-# ProGuard files
-/app/proguard/
-/seeds.txt
-/usage.txt
-/mapping.txt
+.gradle/
+.externalNativeBuild/
+.DS_Store