Move the "no results" code in to the list widget.

lp:~phill-ridout/openlp/no-results (revision 2709)
[SUCCESS] https://ci.openlp.io/job/Branch-01-Pull/1839/
[SUCCESS] https://ci.openlp.io/job/Branch-02-Functional-Tests/1750/
[SUCCESS] https://ci.openlp.io/job/Branch-03-Interface-Tests/1688/
[SUCCESS] https://ci.openlp.io/job/Branch-04a-Windows_Functional_Tests/1434/
[SUCCESS] https://ci.openlp.io/job/Branch-04b-Windows_Interface_Tests/1024/
[SUCCESS] https://ci.openlp.io/job/Branch-05a-Code_...