Feature: Save drawings to my profile

[bensivo]

If I am logged in, then I should be able to save my drawings to my profile, instead of having to download the file to my local machine.

I should be able to:

• Create a new drawing in my profile
• Save a drawing to my profile
• Open any drawing from my profile
• Delete a file from my profile

[bensivo]

If I am not logged in, any UI elements related to profiles should not be shown. The "save" and "load" icons should be replaced by "export" and "import" icons

[bensivo]

Blocked by #34

[bensivo]

Moved #34 to #73