[FIXED] A crash that was regressed due to changes in #73 for #69

```
2019-04-06 11:49:15.514 20635-20635/com.hossainkhan.android.constraintlayout E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.hossainkhan.android.constraintlayout, PID: 20635
    android.util.AndroidRuntimeException: Calling startActivity() from outside of an Activity  context requires the FLAG_ACTIVITY_NEW_TASK flag. Is this really what you want?
        at android.app.ContextImpl.startActivity(ContextImpl.java:912)
        at android.content.ContextWrapper.startActivity(ContextWrapper.java:401)
        at androidx.core.content.ContextCompat.startActivity(ContextCompat.java:248)
        at androidx.browser.customtabs.CustomTabsIntent.launchUrl(CustomTabsIntent.java:263)
        at com.hossainkhan.android.demo.layoutpreview.LayoutPreviewBaseActivity.loadLayoutUrl(LayoutPreviewBaseActivity.kt:165)
        at com.hossainkhan.android.demo.layoutpreview.LayoutPreviewBaseActivity$showLayoutInfo$1.onActionTapped(LayoutPreviewBaseActivity.kt:135)
        at com.andrognito.flashbar.FlashbarView$setPositiveActionTapListener$1.onClick(FlashbarView.kt:329)
        at android.view.View.performClick(View.java:6597)
        at android.view.View.performClickInternal(View.java:6574)
        at android.view.View.access$3100(View.java:778)
        at android.view.View$PerformClick.run(View.java:25885)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
```

Author: hossain-khan

app/src/main/java/com/hossainkhan/android/demo/layoutpreview/LayoutPreviewBaseActivity.kt

@@ -162,7 +162,7 @@ open class LayoutPreviewBaseActivity : AppCompatActivity() {
         builder.setShowTitle(false)
                 .addDefaultShareMenuItem()
         val customTabsIntent = builder.build()
-        customTabsIntent.launchUrl(applicationContext, Uri.parse(viewModel.layoutUrl))
+        customTabsIntent.launchUrl(this, Uri.parse(viewModel.layoutUrl))
     }