Add docker and test application for Bootstrap Theme

[pocky]

Q	A
Branch?	master
Bug fix?	no
New feature?	yes
BC breaks?	no
Deprecations?	no
Related tickets	#50 #59 #60
License	MIT

Like any plugin, this PR add a test application for BootstrapTheme. This application should be used to perform tests and/or be sure all templates works as expected.

• Docker is also available for people who don't have any php/mysql/whatever on their computer (like me).
• Documentation is update for installation with or without docker, application use bootstrap theme by default (thanks to fixtures).

Todolist:

• Merge this PR and add a tag
• Update test application with Sylius 1.9 and 1.10 with legacy_mode: true and tag a new version (close https://github.com/SyliusCrafts/BootstrapTheme/issues/85, merge again https://github.com/SyliusCrafts/BootstrapTheme/issues/92)
• Fix behat tests
• Work on #86 and new directory structure

[4c0n]

Personally I think it's a lot of extra files that you now need to maintain and update, whilst you could just use Sylius-Standard inside the container, but it's up to you.

[pocky]

@4c0n

Personally I think it's a lot of extra files that you now need to maintain and update, whilst you could just use Sylius-Standard inside the container, but it's up to you.

I understand your point but the test application works like any plugin and it's possible to test theme with or without Docker.

I want to open a PR for this subject in sylius/sylius-standard, probably with custom recipes.