Run Ci builds on Mysql 5.6 to test and prevent (some critical) bugs caused by...

Run Ci builds on Mysql 5.6 to test and prevent (some critical) bugs caused by the now-enabled-by-default STRICT_TRANS_TABLES setting.

To prevent such issues let's run all tests against it. Refs https://github.com/piwik/piwik/pull/279

Reused Mysql 5.6 gist provided in https://github.com/travis-ci/travis-ci/issues/1986

.travis.yml

@@ -78,6 +78,21 @@ matrix:
 script: ./travis.sh
 
 before_script:
+  # Setup Mysql 5.6 (source: https://github.com/travis-ci/travis-ci/issues/1986)
+  - "sudo apt-get remove mysql-common mysql-server-5.5 mysql-server-core-5.5 mysql-client-5.5 mysql-client-core-5.5"
+  - "sudo apt-get autoremove"
+  - "sudo apt-get install libaio1"
+  - "wget -O mysql-5.6.14.deb http://dev.mysql.com/get/Downloads/MySQL-5.6/mysql-5.6.14-debian6.0-x86_64.deb/from/http://cdn.mysql.com/"
+  - "sudo dpkg -i mysql-5.6.14.deb"
+  - "sudo cp /opt/mysql/server-5.6/support-files/mysql.server /etc/init.d/mysql.server"
+  - "sudo ln -s /opt/mysql/server-5.6/bin/* /usr/bin/"
+  - "sudo sed -i'' 's/table_cache/table_open_cache/' /etc/mysql/my.cnf"
+  - "sudo sed -i'' 's/log_slow_queries/slow_query_log/' /etc/mysql/my.cnf"
+  - "sudo sed -i'' 's/basedir[^=]\\+=.*$/basedir = \\/opt\\/mysql\\/server-5.6/' /etc/mysql/my.cnf"
+  - "sudo /etc/init.d/mysql.server start"
+  - mysql --version
+  - mysql -e "SELECT VERSION();"
+  # Setup Piwik stack 
   - ./tests/travis/initiate_ui_tests.sh
   - composer self-update
   - composer install