:construction_worker:Extend Travis, add PostgreSQL10.

Add PostgreSQL10 to TravisCI through Docker container.
Use PHP7.2 instead of PHP7.1 as default test environment.
Update to current stable MariaDB 10.2 from stable (GA) 10.1.

.travis.yml

@@ -62,28 +62,34 @@ matrix:
   fast_finish: true
   # Additional check combinations
   include:
-    # PHP7.1, mariadb 10.1
-    - php: '7.1'
-      env: DB=mariadb MARIADB_VERSION=10.1 CODECOV=1
+    # PHP7.2, mariadb 10.2
+    - php: '7.2'
+      env: DB=mariadb MARIADB_VERSION=10.2 CODECOV=1
       # use mariadb instead of MySQL
       addons:
-        mariadb: '10.1'
-    # PHP7.1, PostgreSQL 9.6
-    - php: '7.1'
+        mariadb: '10.2'
+    # PHP7.2, PostgreSQL 9.6
+    - php: '7.2'
       env: DB=pgsql POSTGRESQL_VERSION=9.6 PHPUNITFILE=phpunit-pgsql.xml
       # Use newer postgres than 9.2 default
       addons:
         postgresql: '9.6'
       services:
         - postgresql
-    # PHP7.1, old precise distribution with MySQL 5.5
-    - php: '7.1'
+    # PostgreSQL 10 with Docker container
+    - php: '7.2'
+      env: DB=pgsql POSTGRESQL_VERSION=10 PHPUNITFILE=phpunit-pgsql.xml
+      sudo: required
+      services:
+        - docker
+    # PHP7.2, old precise distribution with MySQL 5.5
+    - php: '7.2'
       env: DB=mysql MYSQL_VERSION=5.5
       dist: precise
       services:
         - mysql
     # MySQL 5.7 with Docker container
-    - php: '7.1'
+    - php: '7.2'
       env: DB=mysql MYSQL_VERSION=5.7
       sudo: required
       services:
@@ -109,6 +115,8 @@ before_install:
   - travis_retry composer self-update
   # Start MySQL 5.7 Docker container, needs some time to come up
   - if [[ "$MYSQL_VERSION" == "5.7" ]]; then sudo service mysql stop; docker run -d -p 3306:3306 -e MYSQL_ALLOW_EMPTY_PASSWORD=yes mysql:5.7 && sleep 25 && docker ps; fi
+  # Start PostgreSQL 10 Docker container, needs some time to come up
+  - if [[ "$POSTGRESQL_VERSION" == "10" ]]; then sudo service postgresql stop; docker run -d -p 5432:5432 postgres:10-alpine && sleep 35 && docker ps; fi
 
 # Install composer dev libs
 install: