Instruction to customize _navigation
Don't encode Unicode chars in database

I prefer to have them readable in the database. Anyway, the charset there is set to UTF8 and should always be so.
Merge branch 'json-utf8-unencoded'
Returning errors on bad calls from P24
Logging the POST when an exception occurs
Merge branch 'log-p24-confirmation'
Better payment buttton label

People probably didn't realize, that clicking the button initiates the
payment. This label should make it more clear.