Enhance schedule to image

[diogotvf7]

What to do

A new feature that allows users to download an image of their currently selected schedule was introduced.
Currently it works fine. However, some suggestions were made - #176 - and are to be implemented:

• As there is a delay between pressing the button and the download starting, a toast saying that the download is in process should be displayed;
• The downloaded file should have the name of the currently selected schedule;
• Add a padding to the screenshot and remove the screenshot button;
• Add our logo (probably in the same place the screenshot button was);
• Remove the grid