bump version to 0.1.1

Currently, react-sinatra can avoid initial overhead by adding the
following configuration code to your app.

@example

  configure do
    React::Sinatra::Pool.pool.reset
  end

lib/react/sinatra/version.rb

@@ -1,5 +1,5 @@
 module React
   module Sinatra
-    VERSION = "0.1.0"
+    VERSION = '0.1.1'
   end
 end