Move net/ldap require into vmpooler.rb

This commit moves net/ldap require from authenticate_ldap in api/helpers to vmpooler.rb. Without this change net/ldap and rubygems are required again every time authenticate_ldap is run.

lib/vmpooler.rb

@@ -4,6 +4,7 @@ module Vmpooler
   require 'date'
   require 'json'
   require 'open-uri'
+  require 'net/ldap'
   require 'rbvmomi'
   require 'redis'
   require 'sinatra/base'

lib/vmpooler/api/helpers.rb

@@ -55,9 +55,6 @@ module Vmpooler
       end
 
       def authenticate_ldap(port, host, user_object, base, username_str, password_str)
-        require 'rubygems'
-        require 'net/ldap'
-
         ldap = Net::LDAP.new(
           :host => host,
           :port => port,