[web] Handle unspecified 'date' or 'time' in JQueryDateTimePicker.process_field_data() dict.get() may return None, which has no attribute strip.

psycopg2
ldap3 < 2
cubicweb-basket
cubicweb-card
cubicweb-comment
cubicweb-file
cubicweb-localperms
cubicweb-tag