Bugfix add trailing slashes for Docker hub API client

[tonybaloney]

Bugfix add trailing slashes for Docker hub API client

Description

The following code snippet fails

from libcloud.container.utils.docker import HubClient
import libcloud.common.exceptions
import libcloud

with open('blah.txt','w') as boo:
    libcloud.enable_debug(boo)
    hub = HubClient()

    try:
        image = hub.get_image('tomcat', '8.0')
    except libcloud.common.exceptions.BaseHTTPError as error:
        print(dir(error))
        print("Waaaaah %s" % error.code)

You can see in the logfile

# -------- begin 4377133392 request ----------
curl -i -X GET -H 'Host: registry.hub.docker.com' -H 'X-LC-Request-ID: 4377133392' -H 'Content-Type: application/json' -H 'Accept-Encoding: gzip,deflate' -H 'User-Agent: libcloud/1.0.0 ' --compress https://registry.hub.docker.com:443/v2/repositories/library/tomcat/tags/8.0
# -------- begin 4377133392:4377127320 response ----------
HTTP/1.1 301 MOVED PERMANENTLY
Transfer-Encoding: chunked
Strict-Transport-Security: max-age=31536000
Server: nginx/1.6.2
Location: https://registry.hub.docker.com/v2/repositories/library/tomcat/tags/8.0/
Date: Thu, 22 Sep 2016 00:21:23 GMT
X-Frame-Options: SAMEORIGIN
Content-Type: text/html; charset=utf-8

0

0

# -------- end 4377133392:4377127320 response ----------

Status

Replace this: describe the PR status. Examples:

• done, ready for review

Checklist (tick everything that applies)

• Code linting (required, can be done after the PR checks)
• Documentation
• Tests
• ICLA (required for bigger changes)

cc @arroyonetworks

[InAnimaTe]

LGTM

[tonybaloney]

merging.