CMS-3765 Replace ExtJS grid - Try move the new TreeGrid to api.ui.treegrid

Moved `app.api.browse.treegrid` module to `api.ui.treegrid`
CMS-3765 Replace ExtJS grid - Try move the new TreeGrid to api.ui.treegrid

Updated interfaces and inheritance chain.
CMS-3765 Replace ExtJS grid - Try move the new TreeGrid to api.ui.treegrid

Removed api.node.Node
CMS-3765 Replace ExtJS grid - Try move the new TreeGrid to api.ui.treegrid

Updated treegrid module position.
Merge pull request #809 from enonic/CMS-3765

CMS-3765 Replace ExtJS grid - Try move the new TreeGrid to api.ui.treegrid
CMS-3731 Replace ExtJS grid - Site content must have S overlay icon

Fixed styles.
Added S icon to the site content.
Merge pull request #810 from enonic/CMS-3731

CMS-3731 Replace ExtJS grid - Site content must have S overlay icon
Merge branch 'master' into osgi
Merge branch 'master' into osgi

Conflicts:
	modules/wem-admin/src/test/resources/com/enonic/wem/admin/rest/resource/module/get_module_by_key_success.json