Add ActiveRecord storage support

[jefflunt]

While writing to a log file is great and all, it completely falls short in the area of reporting. Slicing the metrics in any arbitrarily complex way is a major strength of anything SQL-based.

I'll keep the simple log file storage and basic slowest_actions method around, but want to add :active_record as an option for collector/reporter so that users who want more, or just more fine grained, reporting capabilities can do so easily.

[jefflunt]

This feature is actually being canceled. In talks with other engineers I've been convinced that storage is not really the goal that will help here.

This will be replaced by up to two things:

• Log file injection of custom data, instead of writing to a separate log file
• Log file parsing to get that data back and report on it

How one might store this data to make it reportable is probably a concern that how_slow should not worry about - it should instead emit objects which can be easily serialized into whatever storage (memory, database, file, whatever) of the user's choice.

Essentially, how_slow needs to forever be focused on making it possible to capture the data that a programmer deems necessary to properly measure their app.

I'm even considering not doing log parsing at all, many solutions already exist for this from already existing gems to commercial log analyzers and aggregators.