Add server-side validation of inputs.
Merge branch 'master' of https://github.com/estebanroblesluna/ssurvey

Conflicts:
	modules/ssurvey-webapp/src/main/java/com/ssurvey/web/controllers/SurveyController.java
Merge branch 'master' of https://github.com/estebanroblesluna/ssurvey