LP #1716844: Inserting special characters in a table causes audit log to generate invalid json entries

**Reported in Launchpad by Jaime Sicam last update 28-12-2017 18:37:00

The test case is customer's private data so without permission, I cannot attach it to this bug report.

Basically, install audit_log plugin:
INSTALL PLUGIN audit_log SONAME 'audit_log.so';

Then, import the data in the ticket to Percona Server:
mysql test < test.sql

Then, review the audit log and it contains the insert entry where the JSON format is invalid.