webadmin: LabelWithTextOverflow trims long text and add "..."

In case the lable's text is cropped, the text is visually trimmed.
To let the user know that the text was trimmed '...' are appended
to the string.
The tooltip contains the full text string.

Bug-Url: https://bugzilla.redhat.com/1096662
Change-Id: I3a0c6292b874d0994042366940123b42b38b7a8d
Signed-off-by: Alona Kaplan <alkaplan@redhat.com>