integration.

* bin/evaluate.in (fill-job): New procedure.
(main): Use it to fill informations (nix-name, system) that will later be
added to database.
* doc/cuirass.texi (Database)[Derivation]: Add system and nix_name fields.
(Database)[Builds]: Add id, status, timestamp, starttime and stoptime
fields. Remove output field.
(Database)[Outputs]: New table describing the build outputs.
* src/cuirass/base.scm (build-packages): Add new fields to build object before
adding it to database.
* src/cuirass/database.scm (db-get-build, db-get-builds): New procedures to get
a build by id from database and a list of builds using filter parameters
respectively.
* src/schema.sql (Outputs) : New table.
(Derivations): Add system and nix_name columns.
(Builds): Remove output column and add id, status, timestamp, starttime and
stoptime columns.

* doc/cuirass.texi (Contribution): guix-devel@gnu.org is preferred for
  contributions.

* doc/cuirass.texi (Database): Replace instances of "path" with more accurate
terms.

* doc/cuirass.texi: Add "Database" node.

* doc/cuirass.texi (Introduction): Fix typos and use American English
spelling.

Co-authored-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>

* doc/cuirass.texi (Contributing): Describe how to send patches.

* doc/cuirass.texi (Contributing): Use "bug-cuirass@framalistes.org" email
address.

* bin/cuirass.in (%options): Add "--port" and "-p" command line options.
(show-help): Adapt.
(main): Set default to 8080.  Call 'run-cuirass-server' with this.
* src/cuirass/http.scm (run-cuirass-server): Display the port number.
* doc/cuirass.texi (Invocation): Document new option.

* doc/cuirass.texi (Overview): New chapter.

* doc/cuirass.texi (Continuous Integration): Make it a section of
the 'Introduction' chapter.

* doc/cuirass.texi (Introduction): Write it.

* doc/cuirass.texi: Use "Build automation server" instead of "Continuous
Integration Tool".

* doc/cuirass.texi: New file.
* doc/fdl-1.3.texi: Likewise.
* Makefile.am (info_TEXINFOS, doc_cuirass_TEXINFOS): New variables.
* dir-locals.el: Use the American dictionary for Texinfo mode.
* .gitignore: Update.