Support ubuntu 20.04

[rothvann]

Add changes to work with nodejs command rename in Ubuntu 20.04 to just node
Add mongo installation support (version 4.4)

[justin-castleman]

I have been struggling to get LL installed on a 20.04 system. This seems to be the fix. Any word on when LL admins will merge these changes?

[dandunckelman]

Thanks for this. It passed some initial humps, but I eventually got here:

[LL] Attempting to create your site admin. If this step fails, then it is possible Mongo has not started.
[LL] Attempt to manually start the Mongo service and then run this command:
[LL] cd /usr/local/learninglocker/releases/ll-20210803-ac0803ea165dd49ad74e059a294f5635708d3b80; node cli/dist/server createSiteAdmin YOUR.EMAIL@ADDRESS.COM ORGANISATION_NAME YOUR_PASSWORD
2021-08-03 19:02:54:836 - error: uncaughtException: The gRPC binary module was not installed. This may be fixed by running "npm rebuild"
Original error: Cannot find module '/usr/local/learninglocker/releases/ll-20210803-ac0803ea165dd49ad74e059a294f5635708d3b80/webapp/node_modules/google-gax/node_modules/grpc/src/node/extension_binary/node-v64-linux
-x64-glibc/grpc_node.node'

I tried running npm rebuild from the "webdir":

cd /tmp/learninglocker/webapp
npm rebuild

and got this: https://gist.github.com/dandunckelman/97f729066da3280af9294c13bc7bcf69

Please send help 🛩️ 🚁

[dandunckelman]

To follow up on this, the fix is this: LearningLocker/learninglocker#1600