app compat levels

[anders8]

This library (currently) seems to use appcompat-v7:28.0.0-alpha3, while the released version is 27.1.1.

I'd suggest sticking with non-alpha and non-beta versions, because when adding this, I get this merger issue:

Manifest merger failed : Attribute application@appComponentFactory value=(android.support.v4.app.CoreComponentFactory) from [com.android.support:support-compat:28.0.0-alpha3] AndroidManifest.xml:22:18-91
is also present at [androidx.core:core:1.0.0-alpha3] AndroidManifest.xml:22:18-86 value=(androidx.core.app.CoreComponentFactory).
Suggestion: add 'tools:replace="android:appComponentFactory"' to element at AndroidManifest.xml:12:5-71:19 to override.

It's a nice looking library addition that I'd like to use, but I'm not willing to either drop the rest of my app into alpha code to use it, or mes with overrides and potentially have conflicts of a similar nature.

[tommybuonomo]

Duplicate of #2