🚑 add a prop 'decimalPlaces' for more flexible use

[qinhua]

@xlsdg
Add a prop 'decimalPlaces' for more flexible use.

Just fixed the issue #28 'Decimal places property missing'.

Decimal places property missing #28
What happened to the decimals property? In a much earlier version there was a property that allowed for setting the decimal places. Now it's being ignored and I see no reference to it in the docs.

Cause I encountered this scene, too.
But the original property must place in the config, a little bit inflexible when configurate more than one instance.

The modifications are as follows:
decimalPlaces: {
type: Number,
required: ##false,
default: 0,
}

const config = that.decimalPlaces ?
Object.assign({}, that.options, {
decimalPlaces: that.decimalPlaces,
}) :
that.options;

const instance = new CountUp(
dom,
that.endVal,
config
);

[steveDL]

Is this going to be merged in soon I need to use decimals?

[qinhua]

@xlsdg Please check this code