Fix token authentication on the client side

[Bischoff]

It is currently impossible to use authentication tokens from a python client program.

Reason is that on client side, you do not have the /etc/zvmsdk.conf file where you could define auth = token. The only way to pass such an option is via parameters, but this is not currently implemented.

This PR adds an auth parameter to the ZVM connector methods, which is then passed on to the REST client.

Python program used for testing:

from zvmconnector import connector

# WRONG:
# client = connector.ZVMConnector(
#   connection_type = 'rest', ip_addr = '1.2.3.4', port = '443', ssl_enabled = True, verify = 'feilongCA.crt',
#   token_path = 'token.txt')
# CORRECT:
client = connector.ZVMConnector(
   connection_type = 'rest', ip_addr = '1.2.3.4', port = '443', ssl_enabled = True, verify = 'feilongCA.crt',
   token_path = 'token.txt', auth = 'token')

userid = 'myguest'
vcpus = 2
memory = 2048
user_profile = 'osdflt'
disk_list = [
  {
    'size': "5g",
    'is_boot_disk': True,
    'disk_pool': 'ECKD:vmpool'
  } ]
max_cpu = 4
max_mem = '4G'

guest_create_info = client.send_request(
  'guest_create', userid, vcpus, memory,
  disk_list = disk_list, user_profile = user_profile, max_cpu = max_cpu, max_mem = max_mem)

if guest_create_info['overallRC']:
    raise RuntimeError('Failed to create guest: ' + guest_create_info['errmsg'])

print('Guest created')

[bjhuangr]

@jichenjc please have a review, thanks.

[jichenjc]

@jichenjc please have a review, thanks.

sure will do and merge if no question