[ticket/14448] Use guzzle for remote files uploading
* marc1706/ticket/14448:
[ticket/14448] Correctly pass verify setting if available
[ticket/14448] Let user decide if remote upload certs should be checked
[ticket/14448] Add new vendor files and dirs to clean task
[ticket/14448] Do not try to test remote upload timeout
[ticket/14448] Remove no longer needed guzzle 3.9.3
[ticket/14448] Use GuzzleHttp and try to verify certs
[ticket/14448] Update composer.json and lock file for guzzlehttp
[ticket/14431] Remote avatar uploading
[ticket/14431] Remote avatar uploading