Consider checkstyle implementation

[Crumby]

We should take a look at checkstyle possibilities to keep all classes consistent.

[dsimansk]

I've added a checkstyle via #108 with a couple of rules we used to have on previous utils iterations. However, we could even consider more standard rulesets with more strict approach also, like Google's or Sun's.

https://github.com/checkstyle/checkstyle/tree/master/src/main/resources
http://checkstyle.sourceforge.net/google_style.html
http://checkstyle.sourceforge.net/sun_style.html

[mnovak1]

@Crumby what about to use maven formatter plugin [1] which automatically format the code during build?

[1] https://code.revelc.net/formatter-maven-plugin/

[mnovak1]

Automatic formatting is done in: #394