Blog post for Android development using FastLane

For the first part of https://gitlab.com/gitlab-org/gitlab-ce/issues/46159 I'll be writing a blog post that covers how we got Gitter Android deployments fully automated including code signing and publishing using GitLab CI and FastLane.

This new post would replace https://about.gitlab.com/2018/10/24/setting-up-gitlab-ci-for-android-projects/, so that should probably redirect here.

cc @MadLittleMods @brendan @kencjohnston @williamchia

Edited by Jason Yavorsky