added subcommand keypairs to list SSH key pairs

Example output of this subcommand (one keypair with the name vagrant
is available on Rackspace Servers):

```
$ vagrant rackspace keypairs
==> default: KeyPair Name
==> default: vagrant
```
added subcommand networks to list networks

Example output of this subcommand:

```
$ vagrant rackspace networks
==> default: Network Name                         Network CIDR
==> default: private
==> default: public
==> default: vagrant001                           192.168.3.0/24
==> default: vagrant002                           192.168.4.0/24
==> default: vagrant003                           192.168.5.0/24
```
added subcommand servers to list servers

Example output of this subcommand:

```
$ vagrant rackspace servers
==> devstack: Server Name          State                IPv4 address
==> devstack: devstack             ACTIVE               166.78.18.8
```
rewrote the custom commands section

Also added new commands introduced by #90, #91 and #92.
added column Network ID to the network list

```
==> devstack: Network Name                         Network CIDR             Network ID
==> devstack: private                                                       11111111-1111-1111-1111-111111111111
==> devstack: public                                                        00000000-0000-0000-0000-000000000000
==> devstack: vagrant001                           192.168.3.0/24           c7da5d07-ac80-49ca-8575-8822c71bc758
==> devstack: vagrant002                           192.168.4.0/24           f45ba323-dd21-4999-a5d7-c98a3edfb7a3
==> devstack: vagrant003                           192.168.5.0/24           e49a86df-6c98-42d1-a66b-11c80e1252e1
```
Confirm Rackspace server destruction.

This pull request implements a fix for
mitchellh/vagrant-rackspace#114
Merge pull request #116 from dkinzer/confirm-before-destroy

Confirm Rackspace server destruction.
Merge pull request #116 from dkinzer/confirm-before-destroy

Confirm Rackspace server destruction.
Merge pull request #117 from dkinzer/fix-no-message-error

Fix uninitialized constant error.
Merge pull request #90 from berendt/subcommand_list_keys

added subcommand keypairs to list SSH key pairs
Merge branch 'subcommand_list_networks' of github.com:berendt/vagrant-rackspace into berendt-subcommand_list_networks
Merge branch 'berendt-subcommand_list_networks'

Conflicts:
	lib/vagrant-rackspace/action.rb
	lib/vagrant-rackspace/command/root.rb
Merge branch 'subcommand_list_servers' of github.com:berendt/vagrant-rackspace into berendt-subcommand_list_servers

Conflicts:
	lib/vagrant-rackspace/action.rb
	lib/vagrant-rackspace/command/root.rb
Merge branch 'berendt-subcommand_list_servers'
Merge pull request #94 from berendt/rewrite_custom_commands

rewrote the custom commands section
Add supported for basic private networking to allow interaction with instances over ServiceNet.
Merge branch 'master' of https://github.com/mitchellh/vagrant-rackspace