Small Travis cleanups (#5273)

* Test with no hosts.

* Simplify build matrix.

* Remove after_failure.

.travis.yml

@@ -10,9 +10,6 @@ before_install:
 before_script:
   - 'if [ $TRAVIS_OS_NAME = osx ] ; then ulimit -n 1024 ; fi'
 
-# using separate envs with different TOXENVs creates 4x1 Travis build
-# matrix, which allows us to clearly distinguish which component under
-# test has failed
 matrix:
   include:
     - python: "2.7"
@@ -22,23 +19,14 @@ matrix:
     - python: "2.7"
       env: TOXENV=py27-oldest BOULDER_INTEGRATION=1
       sudo: required
-      after_failure:
-        - sudo cat /var/log/mysql/error.log
-        - ps aux | grep mysql
       services: docker
     - python: "2.6"
       env: TOXENV=py26 BOULDER_INTEGRATION=1
       sudo: required
-      after_failure:
-        - sudo cat /var/log/mysql/error.log
-        - ps aux | grep mysql
       services: docker
     - python: "2.7"
       env: TOXENV=py27_install BOULDER_INTEGRATION=1
       sudo: required
-      after_failure:
-        - sudo cat /var/log/mysql/error.log
-        - ps aux | grep mysql
       services: docker
     - sudo: required
       env: TOXENV=apache_compat
@@ -81,30 +69,18 @@ matrix:
     - python: "3.3"
       env: TOXENV=py33 BOULDER_INTEGRATION=1
       sudo: required
-      after_failure:
-        - sudo cat /var/log/mysql/error.log
-        - ps aux | grep mysql
       services: docker
     - python: "3.4"
       env: TOXENV=py34 BOULDER_INTEGRATION=1
       sudo: required
-      after_failure:
-        - sudo cat /var/log/mysql/error.log
-        - ps aux | grep mysql
       services: docker
     - python: "3.5"
       env: TOXENV=py35 BOULDER_INTEGRATION=1
       sudo: required
-      after_failure:
-        - sudo cat /var/log/mysql/error.log
-        - ps aux | grep mysql
       services: docker
     - python: "3.6"
       env: TOXENV=py36 BOULDER_INTEGRATION=1
       sudo: required
-      after_failure:
-        - sudo cat /var/log/mysql/error.log
-        - ps aux | grep mysql
       services: docker
     - python: "2.7"
       env: TOXENV=nginxroundtrip
@@ -130,17 +106,6 @@ branches:
 sudo: false
 
 addons:
-  # Custom /etc/hosts required for simple verification of http-01
-  # and tls-sni-01, and for certbot_test_nginx
-  hosts:
-    - le.wtf
-    - le1.wtf
-    - le2.wtf
-    - le3.wtf
-    - nginx.wtf
-    - boulder
-    - boulder-mysql
-    - boulder-rabbitmq
   apt:
     sources:
     - augeas