Use alternaltive dimens to use centre_part and fix it

[FireZenk]

closes #69

With this PR the badges will work as expected on any position without removing the center button background:

Based on #78

[FireZenk]

I hosted temporarily the .aar file here to be able to use it with Gradle:

repositories {
  ...
  maven { url 'https://github.com/FireZenk/maven-repo/raw/master/'}
}

dependencies {
  ...
  implementation "com.github.armcha:SpaceNavigationView:1.6.1"
}

[irfaan008]

This looks good.