Upgrade puppetlabs-mysql to 0.6.1.

Puppetlabs-mysql 0.6.1 correctly removes the local ::1 root user in the
account_security manifest. Upgrade to this version to take advantage of
that. Do not upgrade to latest version (0.9.0) to minimize delta that
needs testing.

Change-Id: Ic8265733f1159f34ae0afcccdea4c7d8cd44e3cb
Merge "Upgrade puppetlabs-mysql to 0.6.1."