Automatically require overcommit in CLI file

There's no situation where you can require the CLI code and not also
require the main Overcommit codebase, so move that require statement
into the CLI file.

Author: sds

bin/overcommit

@@ -1,6 +1,5 @@
 #!/usr/bin/env ruby
 
-require 'overcommit'
 require 'overcommit/cli'
 
 logger = Overcommit::Logger.new(STDOUT)

lib/overcommit/cli.rb

@@ -1,3 +1,4 @@
+require 'overcommit'
 require 'optparse'
 
 module Overcommit