Prepare for Sprint 1 "client game"

[yonzarecki]

As sent in the email from the staff, we need to prepare several stuff for our "client game" at the end of sprint 1.

• [x] 2 minutes of describing what our project does and its purpose (without a presentation).
• [x] An installation wiki page - according to which the client will install our plugin.
• [x] A user guide - according to which the client will work with our software
• [x] Use-cases introducing a real case when our program will be useful.

[yonzarecki]

The installation guide is out of date, after #123 is done we'll need to update it.