fix(UserPicker): no messages in userpicker due to lack of i18n

default elgg autocomplete disabled the messages in jquery autocomplete,
this now also applies to the UserPicker
fix(deprecated): Corrected invalid deprecation notice and added more details to few others

Fixes #6869
Merge pull request #6870 from Srokap/ticket_6869

fix(deprecated): Corrected invalid deprecation notice and added more details to few others
Merge pull request #6861 from jdalsem/UserPicker-i18n

fix(UserPicker): no messages in userpicker due to lack of i18n