Remove travis test for 2.6 and 3.3 (#76)

- update README accordingly

Author: cp2boston

.travis.yml

@@ -1,13 +1,11 @@
 language: python
 python:
-  - "2.6"
   - "2.7"
-  - "3.3"
   - "3.4"
   - "3.5"
   - "3.6"
 install:
-  - pip install tox 
+  - pip install tox
 script:
   - tox
 

README.md

@@ -5,7 +5,7 @@ Please check out the [wiki](https://github.com/rosette-api/python/wiki) for addi
 
 ### Installation
 
-The Python binding requires Python 2.6 or greater and is available through pip:
+The Python binding requires Python 2.7+ or 3.4+ and is available through pip:
 
 `pip install rosette_api`