Add autobind decorator and fix Android login screen

mobile/src/ui/BoundSwitch.js

@@ -1,7 +1,7 @@
 import React from 'react'
 import PropTypes from 'prop-types'
 import { View, Switch, Text } from 'react-native'
-import { reactAutoBind } from 'auto-bind2'
+import autobind from 'autobind-decorator'
 
 export class BoundSwitch extends React.Component {
   static propTypes = {
@@ -12,10 +12,10 @@ export class BoundSwitch extends React.Component {
 
   constructor(props) {
     super(props)
-    reactAutoBind(this)
     this.state = props.binder.getFieldState(props.name)
   }
 
+  @autobind
   handleValueChange() {
     const { binder, name } = this.props
     const state = binder.getFieldState(name)