JOINDIN-428 limit cfp app response to 6 week timeframe for events

                            
|Q            |A           |
|---          |---         |
|Bug Fix?     |yes         |
|New Feature? |no          |
|BC Breaks?   |no          |
|Deprecations?|no          |
|Tests Pass?  |yes         |
|Fixed Tickets|#JOINDIN-428|
|License      |MIT         |
|Doc PR       |            |
                            


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This PR is related to https://github.com/joindin/joindin-web2/pull/134 and most likely should be merged and deployed together in a dependency relationship.