[fix] current build URL for Codeship projects

Signed-off-by: Tom Anderson <toanderson@pivotal.io>
replace FixtureFile classes with helper method

Signed-off-by: Tom Anderson <toanderson@pivotal.io>
[tidyup] clean up factory declarations by removing boilerplate

Signed-off-by: Tom Anderson <toanderson@pivotal.io>
[tidyup] remove duplicate tests

Signed-off-by: Tom Anderson <toanderson@pivotal.io>
extract shared examples for JSON payloads
extract shared examples for XML payloads
[tidyup] delete unused shared examples file
[tidyup] clean up Model specs
[fix] correct old test that was invalid
[tidyup] remove old RSpec 2 matchers / non-standard expect syntax
[tidyup] remove Request test helper (duplicate of Feature test helper)
[tidyup] move VCR config to support folder
[tidyup] tracker payload parser
Remove build identifier format validation from TeamCity project.

TeamCity build identifiers no longer have to start with `bt_`.
Allow a custom branch to be specified for CircleCI.