Fix string/bytes issues under python 3. 1) cgi/client.py: override cgi.FieldStorage's make_file so that file is always created in binary/byte mode. This means that json (and xml) are bytes not strings. 2) rest.py: try harder to find dicttoxml in roundup directory or on sys.path. This just worked under python 2 but python 3 only searches sys.path by default and does not search relative like python 2. 3) rest.py: replace headers.getheader call removed from python 3 with equivalent code. 4) rest.py: make value returned from dispatch into bytes not string. 5) test/caseinsensitivedict.py, test/test_CaseInsensitiveDict.py: get code from stackoverflow that implements a case insensitive key dict. So dict['foo'], dict['Foo'] are the same entry. Used for looking up headers in mocked http rewuset header array. 6) test/rest_common.py: rework tests for etags and rest to properly supply bytes to the called routines. Calls to s2b and b2s and use of BytesIO and overriding make_file in cgi.FieldStorage to try to make sure it works under python 3.

# Utility for replacing the simple input field for the timezone with
# a select-field that lists the available values.

import cgi

try:
    import pytz
except ImportError:
    pytz = None


def tzfield(prop, name, default):
    if pytz:
        value = prop.plain()        
        if '' == value:
            value = default
        else:
            try:
                value = "Etc/GMT%+d" % int(value)
            except ValueError:
                pass

        l = ['<select name="%s">' % name]
        for zone in pytz.all_timezones:
            s = ' '
            if zone == value:
                s = 'selected=selected '
            z = cgi.escape(zone)
            l.append('<option %svalue="%s">%s</option>' % (s, z, z))
        l.append('</select>')
        return '\n'.join(l)
        
    else:
        return prop.field()

def init(instance):
    instance.registerUtil('tzfield', tzfield)