salt.cloud.lxc: Optimized salt client
Safebelts for lxc provisionning:

Cloud:
    - Allow to use alternate config prefixes
    - Filter default options

LXC module:
    - Filter default options in create
Report errors when preparation fails

Previously salt daemons could fail to start without giving any
reason, when (for example) chown failed during the startup.
This change doesn't fix anything, but at least reports the error
back to the user.
salt.states.archive: multiple improvments

- add a new keep paramater to optionnaly not delete the archive after extraction
- Fix the traceback in case of tar error by correctly returning a state return mapping
- Correctly handle extra tar options if any by adding defauts ones if only needed
- Pep8
- When silently extracting with tar, be sure that the no output stuff won't be
  handled as a failed extraction.
Add pip_exists_action argument to virtualenv state

If you have some editable packages in a managed virtualenv than
you should be able to set the default action of pip for existing
paths.
lxc: saltify -> bootstrap; lxc & seed: doc improvements
salt.modules.seed: typo
Fix master._clear_old_jobs for ext_pillars with root parameter
Merge pull request #11072 from viraptor/startup_errors

Report errors when preparation fails
Merge pull request #11071 from makinacorpus/lxc

Lxc
Merge pull request #11074 from makinacorpus/archive

salt.states.archive: multiple improvments
Merge pull request #11079 from jarus/virtualenv-exists-already-action

Add pip_exists_action argument to virtualenv state
Typo fix.
Merge pull request #11089 from cachedout/typo_doc_fix

Typo fix.
Spelling correction: exttermal > external
Merge pull request #11086 from krak3n/fix-master._clear_old_jobs-ext_pillar-root

Fix master._clear_old_jobs for ext_pillars with root parameter
Clarify when the new "root" param for git_pillar will be added
Merge pull request #11092 from mgwilliams/lxc

lxc: saltify -> bootstrap; lxc & seed: doc improvements
Merge pull request #11091 from terminalmage/docs

Clarify when the new "root" param for git_pillar will be added
The `__virtual__()` function should only return strings on renames.

If the module is not renaming itself, it should simply return True.
Additionally we now also check for different values on `__virtualname__`
and `__virtual__(), these should always match.`