make sure curl is installed

Author: Stephen von Takach

.travis.yml

@@ -5,6 +5,8 @@ rvm:
   - rbx-2
   - jruby-20mode
 before_install:
+  - sudo apt-get update -qq
+  - sudo apt-get install curl
   - sudo apt-get purge -y openssl libssl-dev
   - curl -o openssl.tar.gz https://www.openssl.org/source/openssl-1.0.2a.tar.gz
   - cd openssl