Standardize editor configs

[samuelgrigolato]

It'd be good to have a standard practice for editor configs, so we avoid diffs like these:

• https://github.com/opensanca/service-validator/pull/16/files#diff-31bb2e13aa4e5ebd6c63035200fb0167: note that the import reordering pollute the intent of the change set.
• d78dd05#diff-97cf78bdb2bf48c0735e1403195894dc: there is nothing locale-related in this commit, just the import reordering.

I've used Google Code Style in the past and those problems were a lot less frequent, not because Google Code Style per se but because they also provide IDEA and Eclipse config files that standardize those things across the team with minimum effort. We can go with them or write our own config files (more work and maintenance burden IMO).