don't write this default attribute
don't write this default attribute

"preserve" is the default value and the OOXML spec sadly does not
contain the definition for xml:space. It is only mentioned in the
documentation so validation against the schema file fails.

Change-Id: I53f804e189dca585fceb4474b96b1b4536d5bde4

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