Add configuration class and modify lookup to use this configuration

To configure the module, you can use :
ProjectHoneypot.configure do
  @api_key = 'API_KEY'
end
To access, the variable, use :
ProjectHoneypot.api_key

The lookup method has been modified to be backward compatible
and use the defined api_key if available.

lib/project-honeypot.rb

@@ -3,8 +3,25 @@ require File.dirname(__FILE__) + "/project_honeypot/url.rb"
 require File.dirname(__FILE__) + "/project_honeypot/base.rb"
 
 module ProjectHoneypot
-  def self.lookup(api_key, url)
-    searcher = Base.new(api_key)
+  class << self
+    attr_accessor :api_key
+
+    def api_key
+      raise "ProjectHoneypot really needs its api_key set to work" unless @api_key
+      @api_key
+    end
+
+    def configure(&block)
+        class_eval(&block)
+    end
+  end
+
+  def self.lookup(api_key_or_url, url=nil)
+    if url.nil?
+      url = api_key_or_url
+      api_key_or_url = ProjectHoneypot.api_key
+    end
+    searcher = Base.new(api_key_or_url)
     searcher.lookup(url)
   end
 end