Fix Logging on newsletter subscribing and CS

In ```Front\Controller\NewsletterController``` the logger was writting errors even if the form was on success.
Moreover, the logger was called with its full NS
modified:   local/modules/Front/Controller/NewsletterController.php
Merge pull request #872 from lovenunu/newsletter

Fix Logging on newsletter subscribing and CS
create API model
create a new API Credential
add missing files
download secure key
render an error page if api id does not exists
create delete api action
create update api event
update translation
create a fake controller for test
create an API firewall checking authorization and request body signature
send headers in http exception response
complete httpException listener
implement httpkernel client for test suite
create /api route for testing if api server is up or down
implement api access verification
create and test customer lis API method
create and test get customer api action
create route for creating a new customer