Fix a typo in travis.yml

Author: ignisf

.travis.yml

@@ -42,7 +42,7 @@ addons:
 bundler_args: --jobs=4 --retry=3
 before_install:
   - if [ "$TRAVIS_OS_NAME" == "linux" ]; then gem update bundler; fi
-  - if [ "$TRAVIS_OS_NAME" == "linux" ]; then gem update --system; f
+  - if [ "$TRAVIS_OS_NAME" == "linux" ]; then gem update --system; fi
   - if [ "$TRAVIS_OS_NAME" == "osx" -a "$TRAVIS_RUBY_VERSION" == "2.0.0" ]; then rvm rubygems current; fi
   - if [ "$TRAVIS_OS_NAME" == "osx" -a "$TRAVIS_RUBY_VERSION" == "system" ]; then sudo gem install bundler; fi
   - if [ "$TRAVIS_OS_NAME" == "osx" -a "$TRAVIS_RUBY_VERSION" != "system" ]; then gem update --system; fi