* src/cuirass/utils.scm (define-enumeration): New macro.
* src/cuirass/database.scm (build-status): New macro.
* src/cuirass/base.scm (build-packages)[hydra-build-status]: Remove.
Use the 'build-status' macro instead.
* doc/cuirass.texi (Sections)[Web API]: New section describing the HTTP API.
* src/cuirass/http.scm (spec->json-string): Move it to utils.scm and rename it
object->json-string.
(object->json-scm): Move it utils.scm.
(handle-*-request): New helpers procedures.
(request-parameters): New procedure to parse a request query.
(url-handler): Add new API's.
* src/cuirass/utils.scm (object->json-scm, object->json-string): Exported
procedures moved from http.scm.
* tests/http.scm: Add various tests on new HTTP API.
* src/cuirass/utils.scm (mkdir-p, make-user-module,
call-with-temporary-directory, with-directory-excursion): Remove because
already defined in guix.
* tests/utils (with-directory-excursion): Remove associated test.
* src/cuirass/base.scm: Use (guix build utils) to provide procedure removed
from (cuirass utils).
* bin/evaluate.in: Ditto.
* bin/cuirass.in: Use "make-user-module" provided by (guix ui).
* src/cuirass/utils.scm (call-with-temporary-directory): New procedure.
* src/cuirass/repo.scm: Use it. New file.
* tests/repo.scm: New tests.
* Makefile.am (dist_pkgmodule_DATA, TESTS): Add them.
