Adds introduction from config to container

Related to #974
Adds introduction to the xml writer
Sets introduction to xml writer
Add optional use of url tag
renamed url to file
Adds introduction page to twig based templates
code formatting
Modified as mentioned on github
changes as of #1042
Add collection
add tutorials class
not needed
remove addPartials from application
move transformation of markdown to the collection
build the right structure in xml
get partials from projectDescriptor
remove setting of partials here
remove setting partials here
remove fluid interface of translater as it was before
remove property - not needed in here