empty string should be raised when rules include `required`

[lcygithub]

empty string should be raised when rules include required,in utils.js ,function required should be

if (!this.isRoot() && this.rule.required && (!this.source.hasOwnProperty(this.field) || this.value === undefined || this.value === null || this.value === ""))

notice the this.value === ""

[tmpfs]

Not so by design, the required field tests whether an expected property is specified. For strings that you do not want to be empty (or consist solely of whitespace) use the whitespace property.

See:

async-validate/plugin/string.js

Lines 22 to 29 in 6fb83e0

	if(this.rule.whitespace) {
	if(/^\s+$/.test(this.value) || this.value === '') {
	this.raise(
	this.reasons.whitespace,
	this.messages.whitespace, this.field);
	}
	}
	}