update virtualenv install instructions

update virtualenv install instructions to be py3.5 compatible

docs/source/installation/virtualenv.rst

@@ -10,30 +10,26 @@ Installation
 Install dependencies:
 ::
 
-    apt-get install git libsmi2ldbl smistrip libxslt1-dev python-dev libevent-dev
+    apt-get install git libsmi2ldbl smistrip libxslt1-dev python3.5-dev libevent-dev default-libmysqlclient-dev
 
 Create the virtualenv
 ::
 
-    virtualenv --python=python2 venv
+    virtualenv --python=python3.5 conpot
 
 Activate the environment
 ::
 
-    source venv/bin/activate
+    source conpot/bin/activate
 
-Upgrade any basic tools in the environment
+Upgrade any basic tools in the environment and deps
 ::
 
     pip install --upgrade pip
     pip install --upgrade setuptools
+    pip install cffi
 
 Install the table version of Conpot from PyPI:
 ::
 
     pip install conpot
-
-
-References
-----------
-* `The Hitchhickers Guide to Python: Virtual Environments <http://docs.python-guide.org/en/latest/dev/virtualenvs/>`_