Count granularity

[dphiffer]

This PR augments the wp_split_tests table in order to combine raw event results into daily aggregate numbers. This is meant to consolidate records so that the table doesn't get bogged down over time. Any time a test is run, and any time there's a conversion, a record gets inserted into the table (granularity set to raw, count set to 1). This PR adds a cron task that runs twice daily and converts the previous days raw results into a single day record with a count set to the sum of the raw results.

• Database migration adds granularity and count columns to the split_tests table (currently we only use raw granularity where each event has a count set to 1, but eventually we will aggregate events into day, week or month counts.)
• Cron mechanism to aggregate raw records from the previous day into day records, twice daily.
• Light refactor of Plugin.php splits functionality into sub-classes.
• Fixes a bug where the default DOM variant wasn't able to track conversion events.
• Adds some basic info to the readme files.

Before running the cron task

After running the cron task

[BatMiles]

should this be committed? I am ignorant of the ways of wordpress databases

[dphiffer]

it makes the dev setup go a lot smoother, imo. I have a practice of clearing out the wp_split_test table, deleting the ACF Pro license key, and then exporting the db (it has admin / password login credentials). I should make a dev setup section in the readme that mentions that.

[BatMiles]

Ooh yes