lvg module bugfix on vg_options patch

When no vg_options are passed to the module, 'vg_options' still exists
in the module.params dict with a value of None, so the default empty string in
the get method is never used. None cannot be "splitted", which backtraced.
use different strategy for RHEL >= 7. Fixes 7763
unarchive: do not assume tar supports -C

Fixes #7777
(But don't rewrite the tar invocation in is_unarchived(), since a
tar that supports "--diff" certainly supports "-C" as well).
move get_distribution_version() to basic.py
Updates django_manage so it populates VIRTUAL_ENV

Virtualenv's activate script sets the VIRTUAL_ENV environment variable to the path of the virtualenv. Checking this variable is a reasonably common way to verify that execution is happening in a virtualenv. It would be convenient if this module's virtualenv handling set this environment variable.
Building Ansible deb requires setuptools
Set default vg_options to empty string
BUGFIX 7811: Adding file existence check when performing mysql import on a .gz or .bz2 file, otherwise Ansible will not notice that the underlying *nix command silently died.
Merge pull request #7809 from rouge8/patch-1

Building Ansible deb requires setuptools
BUGFIX 1178: Adding better existence check in one place.  db_import now fails fast if target does not exist b/c no point going further without the target.
Merge pull request #7808 from joelcrocker/patch-1

Updates django_manage so it populates VIRTUAL_ENV
Merge pull request #7810 from rivik/lvg_options_fix

Set default vg_options to empty string
Merge pull request #7814 from scottbrown/bugfix-7811-mysql_import_does_not_perform_dump_existence_check

BUGFIX for Issue 7811: Adding file existence check when performing mysql import on...
Merge branch 'lvg_fix' of https://github.com/sergevanginderachter/ansible into sergevanginderachter-lvg_fix
Merge branch 'sergevanginderachter-lvg_fix' into devel
Fixed typo in docs
Fixed error in docs
Merge pull request #7822 from sybeck2k/patch-1

Fixed typo in docs
Merge branch '7763' of https://github.com/rmarchei/ansible into rmarchei-7763
Fix get_distribution() for platforms that may have spaces

The new CentOS 7 beta lists the distribution as "CentOS Linux", which
breaks the distribution detection and class loading. This patch fixes
that by taking just the first entry in the string when a space is
detected.