Introduce name property for tuf.formats.ROLE_SCHEMA.
Update tuf.formats.TARGET_SCHEMA and adjust tests.test_formats.py.
Export tuf.tests; mock recursive walk in signercli.py.
Ensure uniqueness of names in making delegations.
Adjust tests.test_signercli to use list of roles.
WIP on adjusting tuf.client.updater to use list of roles.
Find target in order of trust.
Patch mock signercli.make_delegation prompts.
First cut at adapting Konstantin's delegations test.
Neutral refactoring of schema.
Ensure that we explore only delegated roles trusted with the desired target.
Fix several naming and scope errors.

 - "quickstart.py:292: No global (EEXIST) found"
 - "basic_client.py:194: No global (option_parser) found"
 - "rsa_key.py:108: No global (EnvelopeError) found"
 - "rsa_key.py:108: No global (KeygenError) found"
 - "util.py:56: No global (temp_dir) found"
Merge pull request #69 from johnward2/master

Fix several naming and scope errors.
Restructing of delegations integration test.
Test that initial update works with target delegations.
Allow deconfiguration of interposition.
Deconfigure interposition on test repository cleanup.
Test that delegated targets roles cannot breach delegated paths.
Conditionally deconfigure TUF interposition for system tests.
Test that delegation of targets works in order of appearance of roles.