Removed unneeded dependency.

`measured` was something that ended up not getting removed after
testing; this commit removes it as a dependency for this package
Improved code commenting for the patcher.

The patcher was thrown together quickly and lacked documentation that
helps a developer grok the code base. This PR aims to improve the docs
for the patcher module.
Knex now tracks query errors.

Harvester now supports error tracking for queries gone bad. The event
"db.error" is emitted over the socket; it contains the duration, error
code and error message that knex reported back.