Add 'init'/'create-config' functionality

[Kateryna Dovgan]

Add subcommand, creating empty example project and printing a command line for its execution.
For example:

$ python3.7 -m universum init
Writing configs.py... [Done]

Type the following command to launch: python3.7 -m universum -vt=none -fsd=./ -lcp=./configs.py