urgend: PR for MOMathon

Created by: StephanMa

Updated MOMathon-landingpage

1. corrected Event-Date
2. deletion of some tasks and some new text elements
3. intergrated irc-chat via iframe

EditMOM3-Update Saving is no longer possible, if a fatal error arises. A short textmessage appear above until the data was corrected. Fatal errors has to be defined in assertion.template.xml like <xrx:fatal>1</xrx:fatal> Its currently just set for "invalid value", see commit 495ed1e5