Use onBeforeInput so Chrome for Android works. Fix #19 (#47)

Author: 9jaboy

src/index.js

@@ -162,7 +162,7 @@ var MaskedInput = React.createClass({
 
     e.preventDefault()
     this._updateMaskSelection()
-    if (this.mask.input(e.key)) {
+    if (this.mask.input((e.key || e.data))) {
       e.target.value = this.mask.getValue()
       this._updateInputSelection()
       if (this.props.onChange) {
@@ -208,7 +208,7 @@ var MaskedInput = React.createClass({
       maxLength={patternLength}
       onChange={this._onChange}
       onKeyDown={this._onKeyDown}
-      onKeyPress={this._onKeyPress}
+      onBeforeInput={this._onKeyPress}
       onPaste={this._onPaste}
       placeholder={placeholder || this.mask.emptyValue}
       size={size || patternLength}