implement api limiting

app/logical/api_limiter.rb

@@ -0,0 +1,9 @@
+module ApiLimiter
+  def throttled?(ip_addr)
+    key = "#{ip_addr}:#{Time.now.hour}"
+    MEMCACHE.fetch(key, 1.hour, true) {0}
+    MEMCACHE.incr(key).to_i > CurrentUser.user.api_hourly_limit
+  end
+  
+  module_function :throttled?
+end