Require minimum amount of memory during setup

[yaronkoren]

I recently tried setting up Canasta on an AWS server at service level "t2.micro", which offers 1 GB of memory, and trying to do so essentially crashed the server. I assume that was due to the low memory. I upgraded the server to "t2.medium", which has 4 GB of memory, and Canasta is now running fine, and overall 2.2 GB of memory are being used (it's running a single wiki). I don't know what the exact memory requirement of Canasta is, but it would be great if the setup exited out if the amount of available memory was lower than some threshold, just as it exits if Docker is not present, etc. Now I wish I had tried it with the service level between those two, "t2.small" (2 GB of memory), but in any case, hopefully we can agree on some minimum amount of available memory that even the simplest Canasta installation would require.