On some newer android devices the screen tranform matrix already includes the current scale. i.e. the matrix looks like:
```
{
a: scaleX,
b: 0,
c: 0,
d: scaleY,
e: offsetX,
f: offsetY
}
```
where both `scaleX`, and `scaleY` are the current zoom. On other devices the scale is always `1`, and we need to apply our own scaling.
I also added the code to automatically allow webview debgging if the buildType is debuggable. Also, note that you can switch which line is commented out in bundle-compile.sh to get unobfuscated javascript.
The iOS change seems to have a side effect on Android of adding an“Edge Effect” to the web view whenever dragging a block. (Edge effects are the grey curved shadow that appears at the top or bottom of a container when you overscroll. When you drag a block they appear at the top or bottom of the screen)
Adding the `android:overScrollMode=“never”` attribute to the webview means the edge effect doesn’t appear.
* Remove ScratchJrApplication class - it was only being used to initialize the old Google Analytics.
* Change AppUsage (home, school, other, noanswer) from being a prefix on `label` to being a Firebase user property.
* Set the user property when loading the index page - it shouldn’t change for the rest of the session.
PBS Kids has automated testing that looks for uses-sdk with a minimum targetSDK of 23. Even though this gets overridden in the build.gradle settings, adding a line with default values to get through their testing.
Changed android:requiresSmallestWidthDp from 600 to 500.
Android suggests that 600 is a normal value for 7 inch tablets and up. It turns out that many 7-inch tablets are in the 500-600 range (half of the Amazon ones for example).
Fixes#85
