admin-ui: Modify style of table's elements

* Change the position of the pagination menu
* Change the label (text) of the pagination menu
* Apply style on the header of the table and on the pagination menu
admin-ui: Refactor base template
admin-ui: Set home page structure and base style
admin-ui: Replace bootwatch buttons with flat buttons
admin-ui: Minor style modifications for modals
admin-ui: Add specific class for "flat" buttons style
admin-ui: Style modifications for details pages
admin-ui: Modify the structure of top navbars

A navbar has been added with the breadcrumb and the details' subnav.
admin-ui: Update design and style of navigation bars
admin-ui: Remove arrow-pointer and modify style of nav-menus
admin-ui: Unify dropdown lists
admin-ui: Add home top-menu
admin-ui: Update sidebar style
Merge branch 'feature-admin-ui-bars' into feature-admin-ui-style
admin-ui: Update style of select-all button
admin-ui: Update details page style
Merge branch 'feature-admin-ui-style' into feature-admin