Remove the uses-sdk element in favour of the build.gradle config.
Set targetSdkVersion to 19.
Compile to SDK 19 using buildTools 19.

Move the defaultConfig { } block next to the other options for choosing
SDK versions.

Remove the default versionCode and versionName, provide them explicitly
in each product flavor.

Set the beta version code to 14.
Add a suffix to the beta versionName, incremented with each release.