Add same background to App as Spash on android

[RGBboy]

Fixes #591. This should fix the white screen flash Android users see when updating the app. This does not seem to happen when opening an already installed app (that has been opened before) Note: There is still a fade of solid color. I'm not sure how to get rid of this.

In order to test you will need to uninstall the app an reinstall it.

Tester check-list

• Tested on a number of Android devices:

  • Galaxy S8 (Android 7.0/8.0)
  • Galaxy S7 (Android 6.0)

  Optional:

  • Google Pixel 2
  • Galaxy S8 Plus
  • Galaxy S7 Edge
  • Galaxy S6

[stevecottle]

Checked this and is an improvement on the white 👍

[frigus02]

Hm, I think the better option would be to set the SplashTheme as the application/android:theme here:

pride-london-app/android/app/src/main/AndroidManifest.xml

Line 18 in 0eb68ea

android:theme="@style/AppTheme">

Because we use the clean AppTheme once the SplashScreen activity has been loaded:

pride-london-app/android/app/src/main/java/org/prideinlondon/festival/MainActivity.java

Line 12 in 0eb68ea

setTheme(R.style.AppTheme);

I think this is important in case we have any transparent views in React Native.