Ensure empty directories are created

Directories were previously skipped so only created if a file was under
that path. Directories are now explicitly added even if they have no
files in them.
ref #71 : Enables forwarding of the authentication agent connection (like ssh -A user@server.domain)
Downloading files

Usage:
```javascript
mysqldump: {
    files: {
        //Todo local dest and  remote src
        'test1/': 'includes/language', // Copy remove directory to local directory
        'test1/dump.sql': 'index.php',
        'dump.sql': 'index.php'
    },
    options: {
        createDirectories: true,
        directoryPermissions: parseInt(755, 8),
        path: '<%= secret.path %>',
        host: '<%= secret.host %>',
        username: '<%= secret.username %>',
        password: '<%= secret.password %>',
        showProgress: true,
        srcBasePath: '<%= secret.path %>/public_html/', // Base relatively remote path options
        destBasePath: __dirname, //
        mode: 'download' // Or upload
    }
}
```
update error
Merge branch 'master' of github.com:robertprice/grunt-ssh

* 'master' of github.com:robertprice/grunt-ssh:
  Ensure empty directories are created
merge
tidy
update changes