mysql-backup-s3: access denied error when password contains ">" and --all-databases is used

[dbowling]

When using the mysql to S3 backup image, if you pass in the --all-databases option and have a complex password that contains special characters, those appear to be presenting issues with escaping when the SHOW DATABASES command is run.

A password that contains a > in it causes the command to be terminated before it can issue the SHOW DATABASES part. The tool backs up the output and sends it to S3, but the output is really just a series of error messages and not the databases.

Hopefully I'll be able to make a pull request to resolve this at some point, but if I don't I figured I'd get the issue in place at least in case someone else is wondering why they are getting access denied errors when they shouldn't be.