sw html: HTML export test - option with or without "skipImages"
sw html: HTML export test - option with or without "skipImages"

Additionally add loading of HTML document and parsing the document
with libxml - to be able to assert with xpath expression.

Change-Id: I7c62082a124c3705626cd76c8a4cdabc16372399

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core