Adjust localize function so you can opt not to change the timezone if one is set
Adjust localize function so you can opt not to change the timezone if one is set

git-svn-id: 1d840a3b9de75aedc936277cea44c75870a5fe65@14852 25043fe6-1616-0410-a82d-ba8f324cfe61

davidfraser/python-datetime-tz,davidfraser/python-datetime-tz,mithro/python-datetime-tz,matthewhampton/python-datetime-tz,mithro/python-datetime-tz,dave42/python-datetime-tz,j5int/python-datetime-tz,j5int/python-datetime-tz