Remove REE support (EOL imminent)

http://blog.phusion.nl/2012/02/21/ruby-enterprise-edition-1-8-7-2012-02-released-end-of-life-imminent/

.travis.yml

@@ -7,6 +7,5 @@ rvm:
   - 1.9.2
   - 1.9.3
   - jruby-18mode
-  - jruby-19mode
   - rbx-18mode
   - rbx-19mode

README.md

@@ -129,8 +129,8 @@ OmniAuth, how it works, and how to use it.
 
 ## <a name="versions"></a>Supported Ruby Versions
 
-OmniAuth is tested under 1.8.7, 1.9.2, 1.9.3, JRuby, Rubinius (1.8
-mode), and Ruby Enterprise Edition.
+OmniAuth is tested under 1.8.7, 1.9.2, 1.9.3, JRuby (1.8 mode), and Rubinius
+(1.8 and 1.9 modes).
 
 ## <a name="license"></a>License