Initial work for #1

This changes how Service loads and finds the requests. Kernel::load was
a good idea after all. The only drawback is that I have to change
define_request to Aviator.define_request to avoid polluting the global
namespace with the Aviator DSL. That's not a big deal though compared
to the benefits it brings. Running the Service tests now allows
SimpleCov to detect the request definition code. More to come in the
next few commits.
Load request files at exit
Group together files in SimpleCov
Rename request test helper and add class loader
Update klass methods in request tests
Be more efficient in loading/finding the request class for testing
Uncomment the previously commented-out tests
Merge branch 'fix/1' into develop
Use require instead of Kernel.load to fix #1
Merge branch 'fix/1' into develop
Remove extraneous code.
Allow `require aviator` as an alternative to `aviator/core`
Remove extraneous file
Refactor Request definition DSL
Add Service::request_classes
Add indifferent_access
Fix for #4
Merge branch 'fix/4' into develop
Implements #8
Merge branch 'feature/8' into develop