Option to change between rich <html-description> and plain <description>

[Snooz82]

As user i want to have the possibility to change the description format for the TestBench project dump.

Libdoc2TestBench shall use the argument -s / --specdocformat for this option.
If set to RAW, <description> shall be filled.
If set to HTML, <html-description> shall be filled.