Update net.wooga.plugins to version 3.x (#120)

Description
===========

This update will bring the plugin `net.wooga.plugins` to
version `3.x`. With this change the groupname of the gradle
plugin will change during publish so I thought it might be
a good idea to change the project name as well so the groupname
won't include the `atlas` name.

The old groupname `gradle.plugin.net.wooga.gradle:atlas-github`
would become `net.wooga.gradle:github`.

This patch also includes all changes needed for the new
plugin metadata description.

Changes
=======

* ![UPDATE] `net.wooga.plugins` to version `3.x` range
* ![CHANGE] project name and remove `atlas` term
* ![IMPROVE] plugin publish metadata

build.gradle

@@ -16,7 +16,7 @@
  */
 
 plugins {
-    id 'net.wooga.plugins' version '2.2.3'
+    id 'net.wooga.plugins' version '3.1.0'
     id 'net.wooga.snyk' version '0.10.0'
     id "net.wooga.snyk-gradle-plugin" version "0.2.0"
     id "net.wooga.cve-dependency-resolution" version "0.4.0"
@@ -29,12 +29,15 @@ pluginBundle {
     website = 'https://wooga.github.io/atlas-github/'
     vcsUrl = 'https://github.com/wooga/atlas-github'
     tags = ['github', 'publishing']
+}
 
+gradlePlugin {
     plugins {
         github {
             id = 'net.wooga.github'
             displayName = 'Gradle Github plugin'
             description = 'This plugin provides tasks and conventions to publish artifacts to github releases'
+            implementationClass = 'wooga.gradle.github.GithubPlugin'
         }
     }
 }

settings.gradle

@@ -22,4 +22,4 @@ include 'api'
 include 'services:webservice'
 */
 
-rootProject.name = 'atlas-github'
+rootProject.name = 'github'