add em_fiber spec

spec/em/em_fiber_spec.rb

@@ -0,0 +1,22 @@
+# encoding: UTF-8
+if defined? EventMachine && defined? Fiber
+  require 'spec_helper'
+  require 'mysql2/em_fiber'
+
+  describe Mysql2::EM::Fiber::Client do
+    it 'should support queries' do
+      results = []
+      EM.run do
+        Fiber.new {
+          client1 = Mysql2::EM::Fiber::Client.new
+          results = client1.query "SELECT sleep(0.1) as first_query"
+          EM.stop_event_loop
+        }.resume
+      end
+
+      results.first.keys.should include("first_query")
+    end
+  end
+else
+  puts "Either EventMachine or Fibers not available. Skipping tests that use them."
+end