add append feature for sqlite on load fixtures method

[almacbe]

I realize that I forget to add the append feature to SQLite. I've added it to this PR.

[almacbe]

And... how could I test this feature? I am not sure how to create a test in an environment with SQLite config.

[alexislefebvre]

Default configuration of tests uses SQLite:

LiipFunctionalTestBundle/tests/App/config.yml

Line 35 in ba8e654

driver: pdo_sqlite

There is also some tests with MySQL, they are marked with @group mysql and they are ignored by default:

LiipFunctionalTestBundle/tests/Test/WebTestCaseConfigMysqlTest.php

Line 61 in 3bca1f2

* @group mysql

But Travis CI launch them:

LiipFunctionalTestBundle/.travis.yml

Line 46 in 48ec7c6

# In phpunit.xml.dist, tests annotated with "@group mysql" are excluded,

So as long as a test use the append feature, it will be tested with SQLite.

[almacbe]

I have added the test.

[almacbe]

Do you have some update about this PR?

[alexislefebvre]

Thanks!