Make Zencoder URLs interpolation pattern configurable

Pass `:url`, `:hls_url` and `:hls_origin_url` from `zencoder_options`
set in initializer to `ZencoderAttachment.default_options`.

Allows to override the interpolation pattern used to construct urls to
Zencoder generated files. Previously only available for the :path
option.
Use hls_origin host in m3u8 playlists
Do not prefix relative URLs with Default Protocol in Zencoder Attachment
Merge pull request #145 from tf/zencoder-urls

Make Zencoder URLs interpolation pattern configurable
Update Changelog
Update Changelog

Add note about manual registration of audio loop page type.
bump version to 0.5.0
Move spec support files into config and helpers directory

`config` contains configuration of testing libraries. `helpers`
contains doubles and modules mixed into example groups.
Run specs against generated rails app

Add `pageflow-support` gemspec to be used by Pageflow extension
gems. Use `Pageflow::Dummy` to generate dummy test application of
different Rails versions.
Remove dummy app
Use Instafail RSpec formatter
Fix factory girl deprecation warning.

`ignore` is now `transient`.
Fix RSpec version

Tackle deprecation warning generated by 2.99 for update to 3.0 later.
Skip schema:load in travis build
Ignore missing db on db:drop