Make sure distro variable is set if python-apt is installed

Fixes #7295
[get_url] check against lowered stripped sha256sum

The content of the sha256sum attribute should be lowered before comparing it with the calculated sha256sum.

In the following example the used sha256sum uses ABC.. and not abc.. and the check failed. This should not happen.

```
TASK: [get_url url=http://ftp.fau.de/apache/hadoop/common/hadoop-2.4.0/hadoop-2.4.0.tar.gz dest=/home/vagrant/hadoop-2.4.0.tar.gz mode=0644 sha256sum=024326AC68A1A68B5566B10F95609EAAFD9F70CFEB37FCA0E97CBB1674E57C3A] ***
failed: [instance000] => {"failed": true}
msg: The SHA-256 checksum for /home/vagrant/hadoop-2.4.0.tar.gz did not match 024326AC68A1A68B5566B10F95609EAAFD9F70CFEB37FCA0E97CBB1674E57C3A; it was 024326ac68a1a68b5566b10f95609eaafd9f70cfeb37fca0e97cbb1674e57c3a.

FATAL: all hosts have already failed -- aborting
```
Merge pull request #7301 from berendt/check_against_lowered_sha256sum

[get_url] check against lowered stripped sha256sum
Make sure dwim'd relative path ends in a "/" if the original does

Fixes #7296
Add integration tests for group_by module. Fixed bug introduced by ansible/ansible#7273 while also fixing issue described in ansible/ansible#6953
Fix typo
Close fds when running commands from the accelerate daemon

Fixes #7307
Synchronize .deb package version with VERSION file
Merge branch 'devel' of https://github.com/cchurch/ansible into cchurch-devel
[test_apt_repository] Verify that 'python-apt' auto-installs correctly

Remove 'python-apt' before testing the 'apt_repository' module.  The
'apt_repository' module has the smarts to auto-install python-apt.  The
integration test will now assert the correct auto-install behavior.
Close fds when running commands from the accelerate daemon

Fixes #7307
Merge branch 'cchurch-devel' into devel
Add pyc/pyo to ignore list for inventory directories

Fixes #7308
Merge pull request #7313 from mmoya/doc-fixes

Minor typo fix
Merge branch 'debian_version' of https://github.com/drybjed/ansible into drybjed-debian_version
Merge branch 'drybjed-debian_version' into devel
Merge pull request #7304 from jimi-c/issue_7296_synchronize_relative_path

Make sure dwim'd relative path ends in a "/" if the original does
Make sure the default ec2_group egress rule is not removed

Upon a second run, the default egress rule will be removed when a
vpc is specified but no other egress rules were set. This patch
corrects that behavior by removing the default egress rule from the
list of unmatched outbound rules.

Fixes #7309