Option for years only, nominative months, added locale, updated default font

[asxasxasx]

Added ability to use only years, proper names of months (nominative form), added locale property, updated font to new guidelines It should fix calendar issues as well (https://github.com/simonrice/SRMonthPicker/issues/1, https://github.com/simonrice/SRMonthPicker/issues/2)