Remove Python 3.3 support (#416)

Author: cjcodes

.travis.yml

@@ -1,7 +1,6 @@
 language: python
 python:
   - "2.7"
-  - "3.3"
   - "3.4"
   - "3.5"
   - "3.6"

setup.py

@@ -45,7 +45,6 @@
         "Operating System :: OS Independent",
         "Programming Language :: Python",
         "Programming Language :: Python :: 2.7",
-        "Programming Language :: Python :: 3.3",
         "Programming Language :: Python :: 3.4",
         "Programming Language :: Python :: 3.5",
         "Programming Language :: Python :: 3.6",