Release v0.2.1

Changelog (since v0.2.0...v0.2.1)

• bug #19 Apply fixes from StyleCI (@peter-gribanov )
• feature #18 Update Travis CI config (@peter-gribanov)
• feature #17 Change build icons (@peter-gribanov)
• bug #16 Change path to Doctrine config for Symfony 4 (@peter-gribanov)
• bug #15 disable yoda_style (@peter-gribanov)
• feature #14 Add more info about interval types (@peter-gribanov)
• feature Add test local network example (@peter-gribanov)