Fix Ruby builds

The --no-ri flag wasn't recognized on Ruby 2.3 since later versions of
RubyGems are available for that version (RubyGems 3.0.0+).

Remove Ruby 2.2 build (since it is EOL as of June 2018) while we're
here.

appveyor.yml

@@ -4,8 +4,6 @@ clone_depth: 1
 
 environment:
   matrix:
-    - RUBY_FOLDER_VERSION: "22"
-    - RUBY_FOLDER_VERSION: "22-x64"
     - RUBY_FOLDER_VERSION: "23"
     - RUBY_FOLDER_VERSION: "23-x64"
     - RUBY_FOLDER_VERSION: "24"
@@ -39,7 +37,7 @@ install:
   - where ruby
 
   # Install latest version of RubyGems
-  - gem update --system --no-ri --no-rdoc
+  - gem update --system --no-document
   - gem --version
   - where gem