Synchronizing with a remote CardDAV server (#42, #138, #139)

+ Updated contacts sql shema (breaking changes)
+ Fixes
- Removed SabreDAV Server
- Removed Contacts Sharing (awhile, code refactoring)

rainloop/v/0.0.0/app/libraries/Sabre/DAV/Client.php

@@ -315,6 +315,7 @@ class Client {
             // Return headers as part of the response
             CURLOPT_HEADER => true,
             CURLOPT_POSTFIELDS => $body,
+			CURLOPT_USERAGENT => 'RainLoop DAV Client',
             // Automatically follow redirects
             CURLOPT_FOLLOWLOCATION => true,
             CURLOPT_MAXREDIRS => 5,