Handle 'groups=' (empty string) in user module (Linux)

Makes it possible to remove a user from all but the primary group.

Setting 'groups=' is the equivalent to passing '-G ""' to
useradd/usermod, which is interpreted as "no group" on Linux.
added thirsty option to copy
Signed-off-by: Brian Coca <briancoca+dev@gmail.com>
Able to use "environment: " on any task to pass proxy details and other useful settings.  Can be a variable
or a dictionary.
Add example of working with the environment
minor aesthetics tweak
Remove unneccesary quotes from user task
Cleaning up tag compare, getting fully qualified path for executable
Getting fully qualified path for executable
Default expand_lists to True and set it to False for only_if

Fixes #2026 and #2027.
Using new qualified executable
Standarizing module in line with other rabbitmq modules, adding support for setting tracing
Standarizing quotes
Adding aliases
Updating how to run commands in check mode, standarizing quotes
Updating how to run commands in check mode
Add ansible_ssh_user/pass to enable inventory-defined users
Removing duplicate import, adding missing import
Merge pull request #2046 from chrishoffman/importfix

Duplicate/missing import
Fixes for Python 2.4
Fix setup when /sys/block is inaccessible