Make compliant to at least some standard

[aik099]

The baseline for coding style used in the project needs to be established. Right now there is no specific coding standard used and that makes hard to guide contributors into making their PR coding standard compliant.

Connecting project to Scrutinizer CI would make coding standard to be checked automatically as well.

[aik099]

Actually I would recommend making compliant to https://github.com/aik099/CodingStandard instead, which does check/fix a lot of things PSR-2 doesn't even mention.

Main differences:

• TABs instead of SPACESs
• method/function parameter names and local variables names must use snake case (not a big deal considering that currently we have variables named both ways)
• the private properties must be prefixed with _