Merge pull request #684 from aycabta/drop-2.2

Drop Ruby 2.2 from test because of EOL

Author: aycabta

appveyor.yml

@@ -25,8 +25,6 @@ deploy: off
 environment:
   NOBENCHMARK: 1
   matrix:
-    - ruby_version: 22
-    - ruby_version: 22-x64
     - ruby_version: 23
     - ruby_version: 23-x64
     - ruby_version: 24