[WebBundle] Fix invalid html markup for payments forms

Added easier way to change states & hide editing for non super admins
Set differentBillingAddress field optional
Fix specs
[AttributeBundle] Write specs for the LoadMetadataSubscriber
[VariationBundle] Write specs for the LoadMetadataSubscriber
Fix promotion scenarios and nth order rule checker
Test split up running
Fix spec and make test suite executables
Merge pull request #2228 from Sylius/split-travis

Split travis
Removed duplicate stripe.secret_key parameter
[AttributeBundle] Write specs for the container extension
[VariationBundle] Write common spec example for the container extension
Merge pull request #2229 from rvanlaarhoven/patch-1

Removed duplicate stripe.secret_key parameter
Fix legacy payum getNotification
Fix exit code for travis scripts
Tweak the pdf generation
Fix language switching
Fix free product promotion scenario
Fix the formatting discount bug on travis
Merge pull request #2231 from winzou/fix/payum

Fix legacy payum getNotification