Try to run database tests on travis

.travis.yml

@@ -1,4 +1,5 @@
 language: php
+sudo: false
 
 php:
   - 7.0
@@ -7,14 +8,17 @@ php:
   - 5.4
   - 5.3
 
+env:
+  - DB=sqlite
+  - DB=mysql
+  - DB=postgres
+
 matrix:
   fast_finish: true
-  allow_failures:
-    - php: 7.0
 
 before_script:
   - phpenv config-add tests/php.ini
   - composer install
 
 script:
-  - phpunit -c tests/units.sqlite.xml
+  - phpunit -c tests/units.$DB.xml

tests/units.postgres.xml

@@ -7,7 +7,7 @@
     <php>
         <const name="DB_DRIVER" value="postgres" />
         <const name="DB_USERNAME" value="postgres" />
-        <const name="DB_PASSWORD" value="postgres" />
+        <const name="DB_PASSWORD" value="" />
         <const name="DB_NAME" value="kanboard_unit_test" />
     </php>
 </phpunit>