Support requests versions from 2.11.1 onwards

Bug #1155 has been fixed starting with requests 2.11.1 and excluding it
from dependencies causes failures when using latest versions of both
libs together in our project.
Signed-off-by: Yuriy Taraday <yorik.sar@gmail.com>

requirements.txt

-requests==2.5.3
+requests==2.11.1
 six>=1.4.0
 websocket-client==0.32.0
 backports.ssl_match_hostname>=3.5 ; python_version < '3.5'
 ipaddress==1.0.16 ; python_version < '3.3'
-docker-pycreds==0.2.1
\ No newline at end of file
+docker-pycreds==0.2.1

setup.py

@@ -9,7 +9,7 @@ ROOT_DIR = os.path.dirname(__file__)
 SOURCE_DIR = os.path.join(ROOT_DIR)
 
 requirements = [
-    'requests >= 2.5.2, < 2.11',
+    'requests >= 2.5.2, != 2.11.0',
     'six >= 1.4.0',
     'websocket-client >= 0.32.0',
     'docker-pycreds >= 0.2.1'