Ruby Upgrade

This change upgrade the version of Ruby used by the buildpack

Author: nebhale

.ruby-version

@@ -1 +1 @@
-1.9.3-p550
+1.9.3-p551

.travis.yml

@@ -1,9 +1,9 @@
 ---
 language: ruby
 rvm:
-  - 2.1.4
-  - 1.9.3-p550
-before_script: "if [[ $TRAVIS_RUBY_VERSION != '1.9.3-p550' || $TRAVIS_SECURE_ENV_VARS != 'true' ]]; then unset CODECLIMATE_REPO_TOKEN; fi"
+  - 2.1.5
+  - 1.9.3-p551
+before_script: "if [[ $TRAVIS_RUBY_VERSION != '1.9.3-p551' || $TRAVIS_SECURE_ENV_VARS != 'true' ]]; then unset CODECLIMATE_REPO_TOKEN; fi"
 install: bundle install --deployment --without debug
 notifications:
   webhooks: