Fix Shipping Method Calculator form prototype handling

Currently, switching the calculator field in the ShippingMethodType embeds calculator config prototypes under __name__ key, which causes the form to not validate. This commit makes the following changes:
 * use the proper field name (configuration)
 * skip embedding forms for calculators that don't support configuration (currently results in empty text field being embedded)
Behat tests
My account / addresses :
 - improving Behat tests
 - delete cascade on table sylius_user_address
 - listener to directly add the address to the current user (when an address is created) and to directly unset billing and shipping to the user (when an address is deleted)
 - main featurees
My account / addresses :
 - improving routes
 - improving templates
 - finishing "set as default address" features
My account / addresses :
 - translations
My account / addresses :
 - fixing Behat tests
 - now test user is sylius@example.com (like in the fixtures) and his password is sylius
My account / addresses :
 - minor fixes
My account / addresses :
 - isolating routes
My account / addresses :
 - Behat tests
 - fixing addresses test code
My account / addresses :
 - fixing translations
My account / addresses :
 - extending ResourceController
 - using custom action for create instead of using Listener
My account / orders :
 - fixing routes after rebase
My account / password :
 - fixing Behat tests after having changed the login / password of the user test
fixing spec
making CS consistent
Allow to add product with 0.00 price
Test than the product price cannot be negative
Fix Process to keep step sequence after removing step

Currently removing a step from the process leaves gaps in the step sequence and a process is considered closed at the breakpoint, even though there are more steps thereafter. This commmit ensures that proper index sequence is maintained throughout step removal/additions.
Merge pull request #374 from amenophis/minimun-price

Allow to add product with 0.00 price
Merge pull request #375 from Richtermeister/fix-flow-step-remove

Fix Process to keep step sequence after removing step