Implement attaching files functionality

Made My documents default directory
Implement attaching files functionality #651
FilesToAttach is a temporary folder that contains files before linked entity is saved. For example : user selects files that are located on usb device - files are copied to FilesToAttach folder. User ejects USB device - files are not lost. User saves pipe/spool/etc - files are copied from FilesToAttach to Attachments folder, FilesToAttach folder is removed.