Remove image caching from Deployable model

The caching was added because the image details were queried from ImageWarehouse over HTTP. With TIM, it's all stored in DB, so no need for this kind of caching.
remove hooks: unfinished and probably obsolete hook controller, model, tests, views
Enable slow query warnings in development environment

This feature was introduced in Rails 3.2 and is enabled by default in new projects.
Merge pull request #428 from ifarkas/auto_explain

Enable slow query warnings in development environment
Merge pull request #417 from ifarkas/catalog_image_cache

Remove image caching from Deployable model
Merge pull request #421 from martinpovolny/remove_api_hooks

remove hooks