Merge branch 'fix/#1279-#1280-zend-filter-strip-tags-documentation'

Close #1279
Close #1280
Merge branch 'hotfix/#1286-zend-test-docs-headlines'

Close #1286
Update skeleton-application.rst

The installation fails on Ubuntu if the -sdev or --stability parameter is not set.
Merge branch 'hotfix/#1297-dev-mode-for-installation' into develop