Refactor collections based components

[cnouguier]

Since we are using the composable collection.js, it seems that we can unify components of types collection :

• [x] Refactor KGrid
• [ ] Update KBoard
• [ ] Remove KList, and KColumn
• [x] Update KGroupsActivity, KMembersActivity, KOrganizationsActivity and KTagsActivity
• [x] Provide helper components to scroll down / scroll to top : KScrollDown / KScrollToTop
• [x] Add a new initializing state for the Collection when waiting for the first response of the find query