Source install

- Rebased https://github.com/hw-cookbooks/stunnel/pull/13
- Added required ssl-devel
This might not be a valid package location anymore:
```
   - create new file /tmp/kitchen/cache/stunnel.tar.gz[2014-11-06T17:13:52+00:00] WARN: remote_file[/tmp/kitchen/cache/stunnel.tar.gz] cannot be downloaded from ftp://ftp.stunnel.org/stunnel/stunnel-4.56
.tar.gz: 550 Failed to open file.
```

Please verify. This remote location no longer exists.
This is probably your best bet. 
```
ftp://ftp.stunnel.org/stunnel/archive/4.x/stunnel-4.56.tar.gz
```
But the latest version is a 5.x release..

Also, this should be able to be driven by attributes ideally. It might be a little tricky because their file directory layout on their ftp server is pretty unique. You might want to poke around there and then you might, for example, do something like this

```
'attributes/default.rb'
default[:stunnel][:source][:download] = 'ftp://ftp.stunnel.org/stunnel/archive'
default[:stunnel][:source][:major][:version] = '4'
default[:stunnel][:source][:version] = '4.56'

'recipes/source.rb'

remote_file "#{node[:stunnel][:source][:download]}/#{node[:stunnel][:source][:major][:version]}.x/stunnel-#{node[:stunnel][:source][:version]}.tar.gz" do
```