docker_ plugin: disparity of sanitized container names results in missing data

[Daniel Neugebauer]

docker_ plugin sanitizes container names through clean_fieldname in configuration but not when dumping actual values; for example dots (.) are being replaced by underscores (_). This leads to a disparity which affects cpu, memory and network graphs. Graphs will only show -nan instead of a value for affected containers.

Example

For a container name my.container configuration will announce keys containing my_container although values are still printed as my.container.

[Lars Kruse]

fixed in #1213, thanks!