lazy jake wharton versioning

build.gradle

def versionMajor = 3
def versionMinor = 0
def versionPatch = 0
def versionBuild = 0 // bump for dogfood builds, public betas, etc.

android {
  defaultConfig {
    versionCode versionMajor * 10000 + versionMinor * 1000 + versionPatch * 100 + versionBuild
    versionName "${versionMajor}.${versionMinor}.${versionPatch}"
  }
}