Remove support for python 3.5 since it reached EOL

.travis.yml

@@ -1,35 +1,5 @@
 matrix:
     include:
-        - name: "Python 3.5"
-          language: python
-          sudo: required
-          dist: xenial
-          python: 
-            - 3.5
-          before_install:
-            - sudo apt-get -qq update
-            - sudo apt-get install -y ghostscript
-            - sudo apt-get install -y gcc
-          install:
-            - pip install Cython
-            - pip install swagger-spec-validator==2.1.0
-            - pip install connexion==1.4.2
-            - pip install bokeh==0.13.0
-            - pip install tornado==5.0.2
-            - pip install jsonschema==2.6.0
-            - pip install keras==2.3.1
-            - pip install Werkzeug==0.16.1
-            - pip install biopython==1.76
-            - pip install watchdog==0.9.0
-            - pip install coveralls
-            - pip install -e .
-            - mhcflurry-downloads fetch
-          services:
-            - postgresql
-          script:
-            - TEST_FLAG=1 coverage run --source=lib,tools -m unittest discover -v
-          after_success:
-            - coveralls
         - name: "Python 3.6"
           language: python
           sudo: required

docs/install.rst

@@ -5,7 +5,7 @@ Installation
 
 pVACtools is written for Linux but some users have been able to run it successfully on Mac OS X. If you are using Windows you will need to set up a Linux environment, for example by setting up a virtual machine.
 
-pVACtools requires Python 3.5 or above. Before running any installation steps, check the Python version installed on your system:
+pVACtools requires Python 3.6 or above. Before running any installation steps, check the Python version installed on your system:
 
 .. code-block:: none