FreeSWITCH2

Merge pull request #1795 in FS/freeswitch from ~FERNANDOJDK/freeswitch:bugfix/FS-12001-mod_callcenter-can-t-use-mod_mariadb-with-mysql-due-to-keyword-on-table-schema to master

* commit 'd3487dcc3904a8093a7981c0ec5ff57225f5a397':
  FS-12001: [mod_callcenter] Renamed column name from 'system' to 'instance_id' to make mod_callcenter work with MySQL through mod_mariadb