Externalized fixtures.

This enables the use of SyliusCoreBundle without the default fixtures
Merge pull request #1135 from csarrazi/externalize-fixtures

[Fixtures] Externalized fixtures
Force the use of Sylius theme in backend
Set payment total.
Reuse variable.
Merge pull request #1162 from kayue/patch-11

Set payment total.
Set unit price earlier to prevent wrong comparison
added getCountryController() to Addressing bundle
Merge pull request #1163 from umpirsky/fix/item-resolver-set-unit-price

Set unit price earlier to prevent wrong comparison
Merge pull request #1164 from krafas/master

[AddressingBundle] ProvinceController is missing getCountryController() method
Display shipping methods for ALL matching zones on checkout
Adjust required version of Behat in composer.json

Refs #1165.
Merge pull request #1161 from winzou/form/theme

[Web] Force the use of Sylius theme in backend
Fix documentation for OrderItem getter/setter
Merge pull request #1171 from ruudkobes/master

Fix documentation for OrderItem getter/setter
Order taxons with hierarchy in mind.
Merge pull request #1173 from kayue/patch-12

Order taxons with hierarchy in mind.
Move from preUpdate to onFlush

preUpdate event is actually not able to change relation, which is our
case with new InventoryUnit in relation with OrderItem. PreFlush allows
that.
rename output for css assets

In a production environment, when trying to dump the assets, for some reason if the name of the output is backend.css (same of the layout.html.twig), it is overwritten by this and the blueimp gallery is lost.
In the dev environment that doesn't happen.
Renaming the output to something else fixed it for me.
Add expression language to ParametersParser