Includes changes to the Vue container registry component to support
the display of an empty message and error message when invalid
characters are found in the group, project or branch name.
repositories/index.html.haml has been changed to remove the content
and place into Vue component.
Replaces .card-header > hX.card-title with hX.card-header to remove
.card-title. At a occurrence where bold styling is not necessary,
div.card-header is used instead.
By full removal of .card-title at the moment, all workarounds for
BS4's card-title are removed as well.
More information: https://getbootstrap.com/docs/4.0/migration/#panels
Signed-off-by: Takuya Noguchi <takninnovationresearch@gmail.com>