Add roles support for the script module

allows to put scripts directly in a dir within the
role:

 roles/<role>/scripts/..

Same as the copy and template module.

As requested in and closes #2969
roles/x/scripts support: update docs

also added example on where regular tasks fit in
script support for roles: use the files/ directory

instead of an additional scripts/ directory
No need to expanduser() command's chdir argument twice
Document: OpenStack inventory script needs grizzly

The OpenStack Inventory script uses the OS-EXT-IPS:type parameter
to distinguish between fixed and floating IP addresses.
This was only added in the Grizzly release, see
https://bugs.launchpad.net/nova/+bug/1117784

Specify in the docs that this inventory script requires Grizzly
or greater.
provide link to older docs when mentioning older docs
Merge pull request #3017 from sergevanginderachter/roles-script

Add roles support for the script module
Merge pull request #3050 from lorin/os-grizzly-only

Document: OpenStack inventory script needs grizzly
Fix version added field in modules.
Update changelog
Add some FreeBSD facts

added:
 * ansible_distribution
 * ansible_distribution_release 
 * ansible_distribution_version
 * ansible_os_family
 * ansible_pkg_mgr
 * ansible_ssh_host_key_ecdsa_public

Also adds ECDSA public key for all plaforms.
Merge pull request #3055 from kubicek/freebsd

Add some FreeBSD facts
Merge pull request #3054 from maxamillion/maxamillion/docsite

provide link to older docs when mentioning older docs
Merge pull request #3058 from markmandel/devel

Updated vagrant external plugin
Merge pull request #3049 from stoned/cmd-expanduser-once

No need to expanduser() command's chdir argument twice
Use get_bin_path to find mkfs command (issue #2983)
Verify /proc/modules is readable (issue #2990)
Merge pull request #3065 from sfromm/issue2983

Use get_bin_path to find mkfs command (issue #2983)
Merge pull request #3064 from sfromm/issue2990

Verify /proc/modules is readable (issue #2990)
Remove inline comments from inventory tokenizing.