The new user interface uses the flexbox box model has it's primary way
to organize the layout. Unfortunately IE have a non-negligible amount
of subtitle and tricky bugs with its flexbox implementation.
This one was about a `flex-grow: 1` element not growing in a container
which size is defined with `min-height`. See the bug in Microsoft bug
tracker for more details:
https://connect.microsoft.com/IE/feedback/details/802625/Fixes#225
I decided to create my own and not to use a community package, because
1. it's straightforward
2. it's better integrated with our others libs such as EscapeActions
3. monitoring third-party packages evolutions (eg, CSS changes) is a
lot of work.
This is basically the same rationale than for our other generic UI
components such as the Popup/Popover.
This commit also slightly modify the general layout to remove
unnecessary wrapper DOM nodes.
