Finish v0.7.5
#579 added tests for the different scenarios
#579 allow 'fake' metrics from datastores query
- datastore plugins can return a fake metric to be ignored
- updated tests.
#579 updated package with plugin deps
#579 updated removed query tests
#579 updated package deps of datastore plugins
Merge pull request #580 from joola/feature/#579

#579 Support for metricless queries
version bump 0.7.6
Finish v0.7.6