Update sw life-cycle description

Please, update the Sw life-cycle description (inputs, outputs, activities).

Important: it is necessary to be consistent with the information that appears in the rest of the documents that mention the sw life-cycle (D2.4, D4.1 V&V Plan, Hazard and Risk Analysis Methodology -Safety Plan- (D4.2.3) and QA plan)
@janWelte 
@idelatorre
