Python3 support

[stephenpardy]

Does not currently support Python3. First noticed when tried to import client:

ImportError Traceback (most recent call last)
in ()
8 matplotlib.rcParams.update(matplotlib.rcParamsDefault)
9
---> 10 import uws.UWS.client as client
11
12 get_ipython().magic('matplotlib inline')

/usr/local/lib/python3.5/site-packages/uws/UWS/init.py in ()
1 # -- coding: utf-8 --
----> 2 import client
3 import connection
4 import models
5

ImportError: No module named 'client'

The error arises because Python3 needs relative imports to be explicitly defined.

[lupinix]

Yep, just checked that too. Imports and prints can be fixed quite easily using the 2to3 tool. But there are also differences in byte/string handling (see example below). These can be fixed by usage of six

`---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
/home/lupinix/uws-client/venv/lib64/python3.5/base64.py in _input_type_check(s)
517 try:
--> 518 m = memoryview(s)
519 except TypeError as err:

TypeError: memoryview: a bytes-like object is required, not 'str'

The above exception was the direct cause of the following exception:

TypeError Traceback (most recent call last)
in ()
----> 1 cli = client.Client(url, username, password)

/home/lupinix/uws-client/uws/UWS/client.py in init(self, url, user, password, connection)
15 self.connection = connection
16 else:
---> 17 self.connection = UWSConnection.Connection(url, user, password)
18
19 def get_job_list(self, filters=None):

/home/lupinix/uws-client/uws/UWS/connection.py in init(self, url, user, password)
13
14 if user is not None and password is not None:
---> 15 self.auth_string = base64.encodestring('%s:%s' % (user, password))
16 self.auth_string = self.auth_string.replace('\n', '')
17 self.headers = {"Authorization": "Basic %s" % self.auth_string}

/home/lupinix/uws-client/venv/lib64/python3.5/base64.py in encodestring(s)
545 warnings.warn("encodestring() is a deprecated alias, use encodebytes()",
546 DeprecationWarning, 2)
--> 547 return encodebytes(s)
548
549

/home/lupinix/uws-client/venv/lib64/python3.5/base64.py in encodebytes(s)
533 """Encode a bytestring into a bytes object containing multiple lines
534 of base-64 data."""
--> 535 _input_type_check(s)
536 pieces = []
537 for i in range(0, len(s), MAXBINSIZE):

/home/lupinix/uws-client/venv/lib64/python3.5/base64.py in _input_type_check(s)
519 except TypeError as err:
520 msg = "expected bytes-like object, not %s" % s.class.name
--> 521 raise TypeError(msg) from err
522 if m.format not in ('c', 'b', 'B'):
523 msg = ("expected single byte elements, not %r from %s" %

TypeError: expected bytes-like object, not str`

[stephenpardy]

I managed to kludge together a fix for the byte-string issue, and switch the imports and print statements, but then I got a 403 error when trying to submit a request:

UWSError: No permission to access this resource

I checked the credentials on the online version and confirmed that I could actually login.
Perhaps related to the byte-string issue, or something else?

[viogp]

I see a pull request that with the description "Python3 support", could this be integrated?
Right now, with the python3 installation (python3 -m pip install uws-client) something is not working properly:

'''
File ".../python3.8/site-packages/uws/UWS/init.py", line 2, in
import client
ModuleNotFoundError: No module named 'client'

'''

The module client is there, though.