fixed download of files when filename remote contains spaces

[staabm]

Q	A
Issue Type	Bug
Deployer Version	4.2.1
Local Machine OS	ubuntu16.04 lts
Remote Machine OS	ubuntu16.04 lts

php -v
PHP 7.0.16-4+deb.sury.org~xenial+1 (cli) (built: Mar  2 2017 10:36:04) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2017 Zend Technologies
    with Zend OPcache v7.0.16-4+deb.sury.org~xenial+1, Copyright (c) 1999-2017, by Zend Technologies
    with blackfire v1.15.0~linux-x64-non_zts70, https://blackfire.io, by Blackfireio Inc.

Description

the copy using scp fails, as arguments are not properly escaped.

Steps to reproduce

copy a directory which contains file, containing a space in the filename with the following task

task('deploy:update_code', function () {
    download('.', '{{release_path}}');
});

same as #1077 but this time for file download.
only remote paths need escaping as described in #1077

[antonmedv]

Please, read contributing guide.

[staabm]

With this PR we fix a missing escaping of spaces within the remote-scp-part.

Without this downloading a file which contains space in its filename doesnt work.

I will update the changelog after lunch