avocado.core.job_id: Ensure the Job ID is a SHA1

Return the SHA1 of the random data, rather than trusting
that the random number is large enough to fill the 40
character requirement.

This fixes a bug where on occasions the job ID had less
than 40 characters on Travis (later verified to happen
in our machines as well, we just didn't know).

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
Merge pull request #199 from lmr/fix-job-id

avocado.core.job_id: Ensure the Job ID is a SHA1
docs: Add Contribution Guide

Give pointers on how to contribute to the project. Links
to Mailing lists, pointers to the IRC channel and a brief
explanation of the development model.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>
Merge pull request #197 from lmr/contribution-guide

docs: Add Contribution Guide
multiplex: Be deterministic when reading nodes and variables.

When reading nodes and variables, it's important
to keep the order of the structure defined in original
multiplex file, to facilitate debug (with the multiplex plugin)
and to maintain the order of going into node parents.

So we're removing dicts and sets and using OrderedDict.

Signed-off-by: Ruda Moura <rmoura@redhat.com>
avocado.plugins.multiplexer: Display path of nodes by default.

By default, it will now display the paths of the nodes, so
we're not going to show all that structure as it was before.

If you want to see the variables, just pass the option `--contents`
to the plugin.

Here's an example output:

Variants generated:
Variant 1:    /root/hw/cpu/intel, /root/hw/disk/scsi, /root/os/linux/fedora, /root/os/win/winxp, /root/env/debug
Variant 2:    /root/hw/cpu/intel, /root/hw/disk/scsi, /root/os/linux/fedora, /root/os/win/winxp, /root/env/prod
Variant 3:    /root/hw/cpu/intel, /root/hw/disk/scsi, /root/os/linux/fedora, /root/os/win/win7, /root/env/debug

Signed-off-by: Ruda Moura <rmoura@redhat.com>
Merge pull request #189 from ruda/multiplex_ordered_dict

Multiplex:  reading node parents and variables in determinisc way + simple (with paths) output for multiplex plugin