Changes needed for gradle 3.0.1 compatibility

[nesc58]

Some minor changes are needed for gradle 3.0.1 compatibility: in android/build.gradle:

• Remove the buildToolsVersion, gradle now specifies a default and the current value conflicts with that.
• Declare dependencies using api not compile per https://developer.android.com/studio/build/gradle-plugin-3-0-0-migration.html#new_configurations

Thanks

Related issues for our project:

• https://github.com/react-native-community/react-native-svg/issues/581
• https://github.com/AlexanderZaytsev/react-native-i18n/issues/161

[afilp]

I made a PR for this, please let us know if it is OK to be merged. Thanks!