feat(gauge): Intent to ship gauge.enforceMinMax

[netil]

Issue

#2125

Details

Implement enforceMinMax option, which will make data to be displayed in a range of min/max value even value is out of range

gauge: {
  // enforce min/max value.
  // when given value < min, will render as empty value.
  // when value > max, will render to given max value not surpassing it.
  enforceMinMax: true,
  min: 50,  // when given value is 30, gauge will render as empty value.
  max: 100. // when given value is `120`, gauge will render till 100, not surpassing max value.
}

Example of gauge.enforceMinMax=true:

when value=30, gauge.min=50	when value=120, gauge.max=100
not reached min value, so do not draw	surpassing max value, so render till max value

[coveralls]

coverage: 94.399% (+0.01%) from 94.385%
when pulling 34d0903 on netil:gauge#2125
into 8bfc08b on naver:master.