Refactor schema/create-dimension!

Moves groups validation to api front
Requires group_only or grouped_by option to be passed
Refactor: extract execute-with-transaction
Add bang to execute-with-transaction
Remove :pre from add-dimension!

The default should be (when neither of both options were passed):

        `{:group_only false :grouped_by [[]]`

The precondition was preventing assuming that default
Merge pull request #7 from nberger/refactor-create-dimension

Refactor schema/create-dimension!
drop-schema: drop time series fact tables
Merge pull request #8 from nberger/drop-fact-dimension-tables

drop-schema: drop time series fact tables
move execute-with-transaction! to common

uses it whenever possible, to avoid repetition
drop all the fact time series tables inside of transaction
move drop time series tables logic to schema
Adds an integration test for new-fact & get-timeseries
Refactor & fix update/query & range-where
Merge pull request #9 from nberger/execute-with-transaction-everywhere

Move execute-with-transaction! to common. Drop all fact time series in a unique transaction
Merge pull request #10 from nberger/add-fact-tests

Fix query & range-where. Add some tests