Remove "urllib3" requirement (it conflicted with "requests")

Author: mdmintz

requirements.txt

@@ -15,7 +15,6 @@ requests>=2.19.1
 unittest2>=1.1.0
 chardet>=3.0.4
 boto>=2.49.0
-urllib3==1.23
 nose==1.3.7
 ipdb==0.11
 flake8==3.5.0

setup.py

@@ -67,7 +67,6 @@
         'unittest2>=1.1.0',
         'chardet>=3.0.4',
         'boto>=2.49.0',
-        'urllib3==1.23',  # Keep at ==1.23
         'nose==1.3.7',  # Keep at ==1.3.7
         'ipdb==0.11',
         'flake8==3.5.0',