Merge pull request #660 from NicoleRauch/master

Payment reset script.
better usability in managmentTables for activity
checking payments now via javascript in browser
Merge pull request #661 from leider/master

better usability in managmentTables for activity
small adaptions to the management table in activities
Merge pull request #662 from leider/master

small adaptions to the management table in activities
extended text in payment mail
Merge commit 'd2c2c5dc822fc8265e8add5cfd34de72c37c877d'
Merge pull request #663 from leider/master

extended text in payment mail
activity managers can now remove people from the waitinglist
Merge pull request #664 from leider/master

activity managers can now remove people from the waitinglist
Now we get a proper JavaScript object with a member and an addon that is used to display the payments.
Activity can now collect the registration dates of a given participant.
Add registration dates to the activity's management table.
Better error handling and some tests.