Add model specs
Rename DurationCount to Query
Add Query specs
Replace sqlite for pg
Add dummy test app
Set up postgres in dummy test app
Add Activity test model and refactor specs
Refactored parameters format
Extracted CountDuring::QueryOptions
Rename CountDuring to PeriodicCalculations
Support multiple operations on customn column
Version
Clean up query with WITH clause
Add timezone spec
Optimize row selection sub result set for non cumulative queries
Support custom timestamp column
Sort out query specs
Use Time instead of DateTime
Add Query#to_sql method
Add lazy loading