travis: remove PHP < 5.6 and related stuff, phpcs on 7.2, 7.3 not fail

Signed-off-by: Kevin Decherf <kevin@kdecherf.com>

.travis.yml

@@ -1,7 +1,6 @@
 language: php
 
 php:
-    - 5.5
     - 5.6
     - 7.0
     - 7.1
@@ -11,20 +10,10 @@ php:
 
 matrix:
     include:
-        - php: 5.3.3
+        - php: 7.2
-          dist: precise
-          sudo: required
-        - php: 5.3
-          dist: precise
-          sudo: required
-        - php: 5.4
-          dist: precise
-          sudo: required
-        - php: 7.0
           env: CS_FIXER=run
     fast_finish: true
     allow_failures:
-        - php: 7.3
         - php: nightly
 
 # cache vendor dirs
@@ -35,10 +24,6 @@ cache:
 
 before_install:
     - if [ -n "$GH_TOKEN" ]; then composer config github-oauth.github.com ${GH_TOKEN}; fi;
-    # disable TLS for composer because openssl is disabled for PHP 5.3.3 on travis
-    # see: https://blog.travis-ci.com/upcoming_ubuntu_11_10_migration/
-    - if [[ $TRAVIS_PHP_VERSION = 5.3.3 ]]; then composer config -g -- disable-tls true; fi;
-    - if [[ $TRAVIS_PHP_VERSION = 5.3.3 ]]; then composer config -g -- secure-http false; fi;
 
 install:
     - composer self-update