Add a gradle plugin

Resolves #20

.github/readme.md

@@ -8,6 +8,37 @@ vgo is a tool for optimizing vector artwork files that helps ensure your vector
 
 Download the distribution from the releases page and ensure it has execute permission. On macOS & Linux run `chmod +x vgo`.
 
+## Gradle Plugin
+Add the plugin to your buildscript classpath.
+```
+buildscript {
+    repositories {
+        mavenCentral()
+    }
+
+    dependencies {
+        classpath "com.jzbrooks:vgo-plugin:1.4.0"
+    }
+}
+```
+
+Then, in the relevant project, add the plugin.
+```
+plugins {
+    id 'com.jzbrooks.vgo'
+}
+
+vgo {
+    inputs = fileTree(projectDir) {
+        include '**/res/drawable*/*.xml'
+    }
+    outputs = inputs
+    showStatistics = true
+    format = OutputFormat.UNCHANGED
+    indent = 0
+}
+```
+
 ## Command Line Interface
 
 ```

.github/workflows/gradle.yml → .github/workflows/build.yml

@@ -32,11 +32,6 @@ jobs:
       with:
         name: vgo_core_test_results
         path: vgo-core/build/reports/tests/test/
-    - name: archive integration test results
-      uses: actions/upload-artifact@v1
-      with:
-        name: integration_test_results
-        path: vgo/build/reports/tests/integrationTest
     - name: release binary
       run: ./gradlew binary
     - name: archive vgo

.github/workflows/publish.yml

@@ -0,0 +1,37 @@
+name: publish
+
+on:
+  release:
+    types: [released]
+
+jobs:
+  publish:
+    name: Release build and publish
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out code
+        uses: actions/checkout@v2
+
+      - name: set up JDK
+        id: setup-jdk
+        uses: actions/setup-java@v1
+        with:
+          java-version: 11
+
+      - name: Create binary keyring
+        env:
+          GPG_KEY_CONTENTS: ${{ secrets.SIGNING_KEY_SECRET }}
+          SIGNING_KEY_RING_FILE: ${{ secrets.SIGNING_KEY_FILE_PATH }}
+        run: |
+          git fetch --unshallow
+          sudo bash -c "echo '$GPG_KEY_CONTENTS' | base64 -d > '$SIGNING_KEY_RING_FILE'"
+
+      - name: Publish to MavenCentral
+        run: ./gradlew --max-workers 1 --no-daemon publishReleasePublicationToSonatypeRepository closeAndReleaseRepository
+        env:
+          SIGNING_KEY_ID: ${{ secrets.SIGNING_KEY_ID }}
+          SIGNING_PASSWORD: ${{ secrets.SIGNING_KEY_PASSWORD }}
+          SIGNING_KEY_FILE_PATH: ${{ secrets.SIGNING_KEY_FILE_PATH }}
+          OSSRH_USERNAME: ${{ secrets.OSSRH_USERNAME }}
+          OSSRH_PASSWORD: ${{ secrets.OSSRH_PASSWORD }}
+          SONATYPE_PROFILE_ID: ${{ secrets.SONATYPE_PROFILE_ID }}