curl_json plugin: don't complain about not finding expected maps in arrays

The arrays may have mixed maps and scalars.  I'm looking at you Solr.
Renamed all CPU_STATE_* defines for consistency and to avoid conflicts (fixes #812)
Merge pull request #829 from njh/cpu_state

Renamed all CPU_STATE_* defines for consistency and to avoid conflicts
Merge pull request #411 from radford/curl-json-inhomogeneous-arrays

curl_json plugin: don't complain about not finding expected maps in arrays