Organize commands

[mcarmonaa]

This it the borges command organization now:

Usage:
  borges [OPTIONS] <command>

Fetches, organizes and stores repositories.

Help Options:
  -h, --help  Show this help message

Available commands:
  consumer  consume jobs from a queue and process them
  init      initialize the database schema
  pack      quickly pack remote or local repositories into siva files
  producer  create new jobs and put them into the queue
  version   print version

The producer command has been split in several subcommands:

Usage:
  borges [OPTIONS] producer <command>

Help Options:
  -h, --help      Show this help message

Available commands:
  file       produce jobs from file
  mentions   produce jobs from mentions
  republish  requeue jobs from buried queues
  update     update repositories processed previously

About the code, each command is in its own file and it's added to the global parser by the func init() in that file, making easier aggregate more commands.

The subcommands are in their own files too, but the addition is handled in the func init() of the command parent.

The functionality of the commands republish and update aren't implemented in this PR.

Closes #244

[ajnavarro]

If republish and update are not implemented, delete them.

[mcarmonaa]

@ajnavarro there are PRs implementing that functionality #250 #249, just left the structure to make easier the integration with that code. Should I remove them anyway?

[ajnavarro]

Yes, I would prefer to add that structure on the other PRs with the actual functionality.

[erizocosmico]

Why commander and not just Command?

[mcarmonaa]

I saw in the go-flags library that name too, but yes, Command and ExecutableCommand looks better. Will change that.

[erizocosmico]

i'd prefer initializing the commands in the main as it was before instead of having the initializations scattered across all files and sharing a global parser, what do you think?

[mcarmonaa]

I prefer that each command adds itself and don't have an enormous main but whatever all of you agree it's ok for me.

[jfontan]

Shouldn't be fileCmdShortDesc?

[jfontan]

mentionsCmdShortDesc?

[mcarmonaa]

indeed, changing it..