Add test related changes to README and setup.py

Removed the TODO from README and set minimum version of cassandra
driver to 2.6. v2.5 seems to work on certain configurations.

Author: thegeorgeous

README.md

@@ -54,6 +54,3 @@ CQLAlchemy provides all the option available in the cqlengine connection.setup()
 
 ## Tutorial
 For a tutorial on how to use Flask-CQLAlchemy check this [post](http://thegeorgeous.com/2015/06/17/creating-a-tumblelog-with-flask-and-flask-cqlalchemy-I.html)
-
-## TODO/Help Wanted
-* Write tests to check compatibility of different cassandra driver versions

setup.py

@@ -31,7 +31,7 @@
     include_package_data=True,
     platforms='any',
     install_requires=[
-        'cassandra-driver>=2.5',
+        'cassandra-driver>=2.6',
         'blist'
     ],
     classifiers=[