Letsencrypt-plesk

* Upgrade on Windows recreates virtualenv
* Fix issues after upgrade Plesk to Onyx

* Switch from system python to plesk-py27 on all unix OSes (issues 59, 68, 70)

* Install binary dependences from wheels (gcc is not required)
* List of hosted domains and subdomains
* Button under each domain on Websites&Domains
* Submit e-mail and automaticaly install the certificate on the domain
* Monthly task renews certificates issued by Let's Encrypt (according to the name of the certificate)

* ConnectionError on Windows 2012 (issue 103)
* Update certificate with new API in Onyx
* Use certbot packages instead of letsencrypt
* Update subscriber agreement
* Hide disabled webspaces from the domains list

* Windows support (2012 and above, Plesk 12.5 MU24 is required)
* Translation added (ar, cs-CZ, da-DK, de-DE, el-GR, es-ES, fi-FI, fr-FR, he-IL, hu-HU, id-ID, it-IT, ja-JP, ko-KR, ms-MY, nb-NO, nl-NL, pl-PL, pt-BR, pt-PT, ro-RO, ru-RU, sv-SE, th-TH, tl-PH, tr-TR, uk-UA, vi-VN, zh-CN, zh-TW)
* Bugfix: Always put .htaccess in the challenges folder (issues 63 and 82)

* Disable rewrite rules and satisfy authentication (with `.htaccess` file) in challenges directory (issues 13 and 16)
* ExpatError in case Plesk port 8443 is customized (issue 30). Thanks to MatrixCrawler
* Disable HTTPS warnings: localhost is always trusted