Check Jellyfin/Emby version before attempting partial update

[awakenedhaggis]

• add is_partial_update_supported method to each class to validate given version against earliest known supported version
• add get_server_version to get server version number
• add update_partial parameter to user update function, deciding whether or not to allow partial updates

ref: #176

[luigi311]

sorry i didnt see this, i actually prefer this method over what i chose so we can go forward with this instead