Check Sensiolabs recommendations on PSR-1

[castarco]

There are PSR-1 violations in the code (mainly in the DecimalConstants class) reported by Sensiolabs Insight ( https://insight.sensiolabs.com/projects/9a279fbe-2b37-4612-abc0-027a3ad5d69c/analyses/2 ), it would be nice to change the methods names to follow the standard.

[castarco]

Fixed