解决：Multiple dex files define Landroid/support/design/widget/CoordinatorLayout
I had the same error and was able to get my project to build by adding this at the bottom of my gradle file

configurations.all {
    resolutionStrategy.eachDependency { DependencyResolveDetails details ->
        def requested = details.requested
        if (requested.group == 'com.android.support') {
            if (!requested.name.startsWith("multidex")) {
                details.useVersion '27.1.0'
            }
        }
    }
}