Move configuration methods to Fx (#130)

Rather than having `lib/fx/configuration.rb` re-open the `Fx` module, it
makes more sense to have the methods for `Fx.configuration`,
`Fx.configuration=`, and `Fx.configure` live inside `lib/fx.rb`.

lib/fx.rb

@@ -33,6 +33,31 @@ def self.load
     )
   end
 
+  # @return [Fx::Configuration] F(x)'s current configuration
+  def self.configuration
+    @_configuration ||= Configuration.new
+  end
+
+  # Set F(x)'s configuration
+  #
+  # @param config [Fx::Configuration]
+  def self.configuration=(config)
+    @_configuration = config
+  end
+
+  # Modify F(x)'s current configuration
+  #
+  # @yieldparam [Fx::Configuration] config current F(x) config
+  # ```
+  # Fx.configure do |config|
+  #   config.database = Fx::Adapters::Postgres
+  #   config.dump_functions_at_beginning_of_schema = true
+  # end
+  # ```
+  def self.configure
+    yield configuration
+  end
+
   # The current database adapter used by F(x).
   #
   # This defaults to {Fx::Adapters::Postgres} but can be overridden

lib/fx/configuration.rb

@@ -1,29 +1,4 @@
 module Fx
-  # @return [Fx::Configuration] F(x)'s current configuration
-  def self.configuration
-    @_configuration ||= Configuration.new
-  end
-
-  # Set F(x)'s configuration
-  #
-  # @param config [Fx::Configuration]
-  def self.configuration=(config)
-    @_configuration = config
-  end
-
-  # Modify F(x)'s current configuration
-  #
-  # @yieldparam [Fx::Configuration] config current F(x) config
-  # ```
-  # Fx.configure do |config|
-  #   config.database = Fx::Adapters::Postgres
-  #   config.dump_functions_at_beginning_of_schema = true
-  # end
-  # ```
-  def self.configure
-    yield configuration
-  end
-
   # F(x)'s configuration object.
   class Configuration
     # The F(x) database adapter instance to use when executing SQL.