convert group module to be platform sub-classable

Add password support to -c ssh via sshpass

Use the configured remote_tmp even for root

Updates Arch linux packaging files

Added a requirement on euca2ools external package and ec2 url example

Added a README.md to explain the purpose of the directory
Fixed dependencies in PKGBUILD
Added patch to change python binary name for arch users, so they
don't end up using python 3 (python links to python3 by default on arch
linux).

Fix for #1577 (python 2.4 compliance for mysql_user), tested only for syntax, please exercise MySQL fans!

Do not register variable if host has been skipped

Lookup plugin arguments need to be templated

Create a set of all the hosts in a group to prevent duplicates

Fixes #1516.

Executive summary: skipping a host corrupts a variable (when it is registered)

We have a play existing out of multiple tasks that check a condition, if one of these tasks fails we want to skip all next tasks in the playbook. I noticed that if we skip a task because a certain condition is met, and this task has a register-attribute, I loose the value in the variable. Which means we cannot use that variable in subsequent tasks to evaluate because it was skipped:

```
- action: command test -d /some/directory
  register: task

- action: command test -f /some/directory/file
  register: task
  only_if: '${task.rc} == 0'

- action: do something else
  only_if: '${task.rc} == 0'
```

In the above example, if the second task is skipped (because the first failed), the third action will end with a "SyntaxError: invalid syntax" complaining about the unsubstituted ${task.rc} (even though it was set by the first task and used for skipping the second).

The following play demonstrates the problem:

```
- name: Test register on ignored tasks
  hosts: all
  gather_facts: no

  vars:
    skip: true
    task: { 'rc': 666 }

  tasks:
  - action: debug msg='skip = ${skip}, task.rc = ${task.rc}'

  - name: Skip this task, just to test if task has changed
    action: command ls
    register: task
    only_if: '${skip} != True'

  - action: debug msg='skip = ${skip}, task.rc = ${task.rc}'

  - name: Now use task value
    action: command echo 'Works !'
    only_if: '${task.rc} == 0'
```

And the enclosed fix, fixes the above problem.

Keep hostvars from being templated

Use all available vars for hosts:, user: and sudo_user:

Print the task name (if any) when complaining

Make parameterized playbook includes work with vars as a list

After spending 10 minutes to find which playbook had an action/local_action missing, I changed the error to include the task name (if set). The error eventually was caused because I added a name to a task, but the dash before the existing action was not removed.

Fixes #1610.

Try to ensure the entire value is quoted

add bsd md5 support to fetch module

Templating fixes and features

minor linux user module fixups

Previously, "a $ string $var" would not have gotten replaced at all.