Release Jetpants 0.8.2

* Add methods for probing table schema, and linking tables to pools
* Bundled online_schema_change plugin, a wrapper around Percona's
  pt-online-schema-change tool that allows clean management of
  ALTER TABLE, especially on shards
* Bundled capacity_plan plugin, which can track and generate reports
  on data set growth rate, hardware accounting, and more
* Bundled upgrade_helper plugin, which adds Jetpants commands for
  managing a major MySQL upgrade and interacting with a few more
  tools from Percona Toolkit
* Cleaned up spare node related logic, and made it easier for custom
  plugins to implement new validation rules around spares
* Add an example script that uses Jetpants as a library. This script
  can be used to count all rows in your database topology, quickly and
  concurrently, via doing chunked count queries on standby slaves
* Several minor bugfixes and internal code refactoring