If the value of a classifier was zero (or any other value that
interprets as boolean False), it used to be coverted to an empty entry.
This makes sure that the value gets correctly ropagated.
- add IterationResult-level classifiers that get merged into every
added metric (saves having to pass the same classifiers to each
metric added).
- Added a global alias to csv result processor's use_all_classifiers
attribute.
- Adding "classifiers" field to Metric objects. This is a dict mapping
classifier names (arbitrary strings) to corresponding values for that
specific metrics. This is to allow extensions to add
extension-specific annotations to metric that could be handled in a
generic way (e.g. by result processors).
- Updating telemetry workload to add classifiers for the url and internal
iteration (or "time") for a particular result.
- Updating csv result processor with the option to use classifiers to
add columns to results.csv (either using all classifiers found, or
only for the specific ones listed).
