Update Ruby to 2.2.1

.ruby-version

@@ -1 +1 @@
-2.2.0
+2.2.1

.travis.yml

@@ -10,6 +10,7 @@ rvm:
   - 2.1.4
   - 2.1.5
   - 2.2.0
+  - 2.2.1
 script: bundle exec rspec
 notifications:
   email:

README.md

@@ -92,7 +92,7 @@ WPScan comes pre-installed on the following Linux distributions:
 
 Prerequisites:
 
-- Ruby >= 1.9.2 - Recommended: 2.2.0
+- Ruby >= 1.9.2 - Recommended: 2.2.1
 - Curl >= 7.21  - Recommended: latest - FYI the 7.29 has a segfault
 - RubyGems      - Recommended: latest
 - Git
@@ -155,8 +155,8 @@ Apple Xcode, Command Line Tools and the libffi are needed (to be able to install
     curl -sSL https://get.rvm.io | bash -s stable
     source ~/.rvm/scripts/rvm
     echo "source ~/.rvm/scripts/rvm" >> ~/.bashrc
-    rvm install 2.2.0
-    rvm use 2.2.0 --default
+    rvm install 2.2.1
+    rvm use 2.2.1 --default
     echo "gem: --no-ri --no-rdoc" > ~/.gemrc
     gem install bundler
     git clone https://github.com/wpscanteam/wpscan.git