Configuration for the release task.

Contains the following values:

name:      The name of your application
version:   The version of your application
dev?:      Is this release being built in dev mode
env:       The mix environment the app should be build for
erl:       The binary containing all options to pass to erl
upgrade?:  Is this release an upgrade?
verbosity: The verbosity level, one of [silent|quiet|normal|verbose]