Uses secure RubyGems URL
Merge pull request #1179 from pmcconnell/patch-1

Uses secure RubyGems URL
Removes some confusion from ContenTypeDetector methods
Fixes a test that caused an error in Ruby 2.0.0
https in the Gemfile.lock
add -layers 'optimize' flag to animated gif convert cmds
animated gif option formatting
fix tests from animated gif layers optimize change
Clarify tests for frame dimensions
Add ruby-2.0.0 to travis CI
Remove the Gemfile.lock
Update the Appraisals so my environment tests correctly
Add expiring_url as an alias for url
Add a test for expiring_url within filesystem storage
Use the right aws-sdk version in the README
Add support for generators.

This is a processing step that occurs between processing the original, and
processing the remaining styles. It takes the (optionally processed) original
as input, and outputs any or all of the styles (which are then optionally
processed as normal).

This allows a significant optimization in the common scenario of generating
multiple thumbnails from the source image. The usual processing pipeline could
be replaced with a generator which generates all the output files in a single
invocation, possibly with intermediate downsampling for further performance
gains.
Create tables where needed in tests.

This fixes failures when some tests in this file are run in isolation.
Handle processing errors in generators just like other processors.