Some improvements before 2.0!

[jacquesbh]

• Use admin route directly in config
• Indent configuration for 4 spaces & move ui elements config
• Use existing parameter instead of unexisting env
• Run PHP CS in tests
• Fix some PHP code using php cs fixer
• Update TESTING.md according to the new release
• Add a test.all target to run all tests in once
• Reformat TESTING.md