Add support to Source mirroring

[Free Ekanayaka]

|--==> "OS" == Otavio Salvador <otavio@debian.org> writes:

  OS> [1  <multipart/mixed (7bit)>]
  OS> [1.1  <text/plain (7bit)>]
  OS> Hello folks,

  OS> Today I received a mail asking to include support to mirror source of
  OS> packages too. I this we can deal with it like:

  OS> Add, on configuration file, an option get_sources and by default, when
  OS> this is set, got all sources of package we are getting in backend.

  OS> And on backend, allow to the source_only option so we can use it to
  OS> get only the source against one filter ;-)

Thinking it twice maybe it would be cleaner to replace the source_only
option with a get_binaries one.

Both option might be used  in the general  configuration part, or on a
per-backend basis (as you already did AFAICS), e.g. :

;; What should I get?
get_binaries = true
get_sources = false

;; My backend with sources only
[my_backend]

get_binaries = false
get_sources = true

Cheers,

Free Ekanayaka