Added section on union data sources
Merge branch 'master' into fix-datasource-doc
fixed typo and added info that union can take any number of dataSources
typo: s/metric_value/metric_name/
typo: s/metric_value/metric_name/ and added quotes
Added info to better explain how to use pagingSpec
clarified that dimensions and metrics are given in String arrays
clarified that dimension and metric can be String too, not just object
fix query/wait emitted twice
Merge pull request #831 from metamx/fix-query-wait-emmitted

fix query/wait being emitted twice
Merge pull request #828 from metamx/fix-query-docs

Fix query docs
fixes typo
Merge pull request #832 from metamx/fix-query-docs

fixes typo
skip timestamp checking, remove duplicate code

1) No need compare all timestamps when all the values are within range
2) remove redundant code.
Merge branch 'master' into fix-datasource-doc
fixed typo, added note on matching schema requirement for unioned data sources
Merge pull request #814 from metamx/fix-datasource-doc

Added section on union data sources
fix non-deterministic test
fix dimension exclusions for timestamp and aggs

- also added tests
Include origin when creating the cacheKey for period Grans