XWIKI-10165: Hide the content bar when asked

* Take into account the value of '$displayContentMenu' in 'edit' mode
XWIKI-10165: Hide the content bar when asked

* Create and use the '$displayEditMenu' for this purpose
XWIKI-10165: Hide the content bar when asked

* Comment the variables '$displayContentMenu' and '$displayEditMenu'
Merge pull request #267 from woshilapin/XWIKI-10165

XWIKI-10165: Hide the content bar when asked