2015-08-25

Enhancements:
 - Implements close mechanism for torque renderer to free canvas' images
 - Base adaptor exposes and calls renderers' close if available
 - Blend renderer calls close on all renderers

Bug fixes:
 - Honor RenderCache ttl option

Announcements:
 - Do not report png cache size on renderers
 - Uses [cartodb/node-canvas@1.2.7-cdb1](https://github.com/CartoDB/node-canvas/releases/tag/1.2.7-cdb1)