Add logging

[msrb]

LSP agent in Che doesn't listen on server's stderr, so logs printed there don't show anywhere. The viable option could be sending them to a file.

Note there already is some very basic file logging, but the file is nowhere to be found in Che workspace. I guess the current working directory is not writeable for the server (use $HOME maybe?).

[invincibleJai]

@msrb log file bayesian.log is created in current working directory (i.e. /projects/ for Che workspaces) , have tested with #9 it'll be created in (/home/user/che/ls-bayesian) for Che workspaces

[samuzzal-choudhury]

@invincibleJai this sounds good to me as Mario pointed out that the log location /home/user/che/ is going to be in accordance with other agents.

@msrb I think this issue can be used for working on redirecting server's stderr to the log file. Please correct me if you think otherwise.

[jeffmaury]

Would be fine if we can tune the log level through another env var. Also note the log file is an absolute UNIX file path that causes isssues while debugging on Windows