Merge pull request #3 from gspencergoog/cirrus_switch

Switch to using Cirrus instead of Travis, and add a check for publishability. This consisted of copying the setup from the flutter/plugins repo and renaming PLUGIN_SHARDING to BUILD_SHARDING.

Moves packages/palette_generator/example/image_colors up one directory level to packages/palette_generator/example, since there's only the one example, and the plugin_tools and pub only seem to allow one example. That's really too bad, but I don't feel like fighting it at the moment.

Fixed a formatting error (that was probably due to dartfmt changing), and an analyzer error (due to an updated analyzer).

Author: gspencergoog

.cirrus.yml

@@ -0,0 +1,55 @@
+task:
+  container:
+    image: cirrusci/flutter:latest
+    cpu: 4
+    memory: 8G
+  upgrade_script:
+    - flutter channel master
+    - flutter upgrade
+    - git fetch origin master
+  activate_script: pub global activate flutter_plugin_tools
+  matrix:
+    - name: publishable
+      script: ./script/check_publish.sh
+    - name: test+format
+      install_script:
+        - wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
+        - sudo apt-add-repository "deb http://apt.llvm.org/xenial/ llvm-toolchain-xenial-5.0 main"
+        - sudo apt-get update
+        - sudo apt-get install -y --allow-unauthenticated clang-format-5.0
+      format_script: ./script/incremental_build.sh format --travis --clang-format=clang-format-5.0
+      test_script: ./script/incremental_build.sh test
+    - name: analyze
+      script: ./script/incremental_build.sh analyze
+    - name: build-apks+java-test
+      env:
+        matrix:
+          BUILD_SHARDING: "--shardIndex 0 --shardCount 2"
+          BUILD_SHARDING: "--shardIndex 1 --shardCount 2"
+      script:
+        - ./script/incremental_build.sh build-examples --apk
+        - ./script/incremental_build.sh java-test  # must come after apk build
+
+task:
+  name: build-ipas
+  osx_instance:
+    image: high-sierra-xcode-9.4
+  env:
+    PATH: $PATH:/usr/local/bin
+    matrix:
+      BUILD_SHARDING: "--shardIndex 0 --shardCount 2"
+      BUILD_SHARDING: "--shardIndex 1 --shardCount 2"
+  setup_script:
+    - brew update
+    - brew install libimobiledevice
+    - brew install ideviceinstaller
+    - brew install ios-deploy
+    - pod repo update
+    - git clone https://github.com/flutter/flutter.git
+    - git fetch origin master
+    - export PATH=`pwd`/flutter/bin:`pwd`/flutter/bin/cache/dart-sdk/bin:$PATH
+    - flutter doctor
+    - pub global activate flutter_plugin_tools
+  build_script:
+    - export PATH=`pwd`/flutter/bin:`pwd`/flutter/bin/cache/dart-sdk/bin:$PATH
+    - ./script/incremental_build.sh build-examples --ipa