url_escape with a "quote" option (not quote_plus)

[sylvainvivien]

Could you add an option for the url_escape method that don't use
quote_plus but only quote.

Something like this :

def url_escape(value, quote_plus=True):
"""Returns a valid URL-encoded version of the given value."""
if quote_plus:
return urllib.quote_plus(utf8(value))
return urllib.quote(utf8(value))