Updated CodeMirror
Added HTML element
Added application CSS editor
Merge branch 'feature/html-css-element' into release/3.0.4.0

Conflicts:
	src/Mapbender/CoreBundle/Resources/translations/messages.de.xlf
	src/Mapbender/CoreBundle/Resources/translations/messages.en.xlf
	src/Mapbender/CoreBundle/Resources/views/corebundle.trans.twig
	src/Mapbender/ManagerBundle/Form/Type/ApplicationType.php
	src/Mapbender/ManagerBundle/Resources/translations/messages.de.xlf
	src/Mapbender/ManagerBundle/Resources/translations/messages.en.xlf
	src/Mapbender/ManagerBundle/Resources/views/Application/edit.html.twig