Use different User-Agent in RSpec HTTP requests

RSpecs that send actual HTTP requests to download assets should
use a non-default User-Agent to make it clear the requests are
coming from tests.
Merge branch 'master' into user-agent-fix

Conflicts:
	spec/bin/compile_spec.rb

Sync'ed my fork with the upstream repo.
Merge pull request #128 from ThomWright/user-agent-fix

User agent fix - update to RSpecs