RADAR-base/RADAR-Questionnaire: RADAR-Questionnaire v0.5.5

Changes since v0.5.2 Includes Initial refactoring and some fixes Intends to fix issue #152 Partially fixes issue #151 Intends to fix issue #150 Added logic to handle DEMO questions. Now nothing is done after the completion of he DEMO questions. Also now possible to add more DEMO questions if required, it just need to contain DEMO in its name like PHQ8_DEMO. Fixes #136, point 4 in #146 and #144 Fixes an issue with displaying extra info like warning in the home page task info. Fixes issue with merging answers from 2 separate questionnaires. Fixes Travis buil