+ [ios] Add mention danger plugin

.travis.yml

@@ -1,7 +1,7 @@
 language: objective-c
 rvm: 2.0.0
 before_install:
-  - gem install danger danger-xcode_summary xcpretty xcpretty-json-formatter
+  - gem install danger danger-xcode_summary danger-mention xcpretty xcpretty-json-formatter
 script:
   - xcodebuild -project ios/sdk/WeexSDK.xcodeproj test -scheme WeexSDKTests CODE_SIGN_IDENTITY="" CODE_SIGNING_REQUIRED=NO -destination 'platform=iOS Simulator,name=iPhone 6' | XCPRETTY_JSON_FILE_OUTPUT=ios/sdk/xcodebuild.json xcpretty -f `xcpretty-json-formatter`
   - bundle exec danger

Dangerfile

@@ -4,7 +4,7 @@ warn("Big PR") if git.lines_of_code > 500
 xcode_summary.ignored_files = '**/Pods/**'
 xcode_summary.report 'ios/sdk/xcodebuild.json'
 
-
+mention.run
 
 # Find reviewers without parsing blame information
 # from files matching to 'Pods/*'

Gemfile

@@ -1,10 +1,10 @@
 # frozen_string_literal: true
 source "https://rubygems.org"
 
-gem "xcpretty"
-gem "xcpretty-json-formatter"
-gem "danger"
-gem "danger-xcode_summary"
+# gem "xcpretty"
+# gem "xcpretty-json-formatter"
+# gem "danger"
+# gem "danger-xcode_summary"
 
 # gem "danger-mention"