[views] csvexport accept an empty rset (closes #4236928) When you tried to apply the 'csvexport' view on an empty rset, the view couldn't be selected and you got a HTTP 500 error. Also add two new test cases.

* {
  color: #000 !important;
}

div#popupLoginBox,
div#popupLoginBox,
img#logo, div.header,
#navColumnLeft, #navColumnRight,
#footer {
  display: none
}

div#pageContent{
  border: none;
}