chore(travis): update and install setuptools and pip

.travis.yml

@@ -1,8 +1,6 @@
 language: python
 
-dist: trusty
-
-sudo: true
+dist: xenial
 
 addons:
   apt:
@@ -18,8 +16,7 @@ services:
 
 install:
   - pip install flake8==3.3.0
-  - flake8 . --count --select=E901,E999,F821,F822,F823 --show-source --statistics
-  - sudo rm /etc/apt/sources.list.d/docker.list
+  - sudo -H python3 -m pip install --upgrade setuptools pip
   - sudo apt-get install hhvm && rm -rf /home/travis/.kiex/
   - sudo apt-get purge -y mysql-common mysql-server mysql-client
   - nvm install v7.10.0