fix grammar and syntax
Merge pull request #338 from greg0ire/documentation_improvements

Documentation improvements
replace locale with a language

The locale makes the tests fail.
Merge pull request #340 from greg0ire/fix_unit_tests

replace locale with a language
Added datepicker
Merge pull request #341 from Bladrak/datepicker

Added datepicker
code simplification

the slug will always be null, so…
make the parent field mandatory if the root exists

@see #337