Display shipping methods for ALL matching zones on checkout
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
Remove unused functions
Add really used functions
Merge pull request #1174 from winzou/fix/item

[Core] Move from preUpdate to onFlush
Rename expression to expr
Merge pull request #1180 from amenophis/expression

Use expressionLanguage into ParametersParser
Fix release ONHOLD sold units

1. Put counting $quantity before change state :) coz we never release ONHOLD.

2. When backorders are off and you try to buy last product-variant (on_hand=1) not available on demand (available_on_demand=0)
inventoryOperator->decrease($units); throws InsufficientStockException
isStockSufficient function doesn't know that ONHOLD units waiting for our order.

We can release ONHOLD units before decrease (like in this PR)
or we should send to decrease fucntion $quantity var.
Merge pull request #1181 from ramol/master

Fix release ONHOLD sold units
Fixed docblock
Merge pull request #1184 from umpirsky/fix/minor-fix-10-03-2014

Fixed docblock
Add missing addDefaultsIfNotSet() calls

An addDefaultsIfNotSet() method is not called on every array element of config tree. As the result, config is not properly populated with default values.
Merge pull request #1185 from 20th/master

Add missing addDefaultsIfNotSet() calls in InventoryBundle config
Modify _variant.html.twig in order to be able to see images at generated pdf invoices
Merge pull request #1145 from foopang/fix/issue-1145

Not able to select a shipping method where there are both shipping zone and product restricted zone that match user's shipping address
Added parameter 'true' to imagine filter
Adding CONTRIBUTING.md file

Inspired by blog post: http://sylius.org/blog/contributing-guide
Merge pull request #1189 from JRomeoSalazar/pdf-images

Images at PDF format invoice