Custom validatable icon rendering

[skuzoluk]

• First i had to fix "Image.resizeMode.contain" bug. Because this variable is no longer exposing in RN 0.57
• The reason to implement this feature is to use any custom element as the left icon depending on the validation state. For example i created a sample renderer function to render react-native-vector-icons/Ionicons:

const getValidationRenderer = (icon, defaultColor, changeIconOnValidation) => {
      return (showValidation, isValid) => {
        let color = defaultColor;
        let iconName = icon;
        let size = 22;
        if (showValidation) {
          color = isValid ? Colors.green10 : Colors.red10;
          if (changeIconOnValidation) {
            iconName = isValid ? 'md-checkmark' : 'md-close';
          }
        }
        return (
          <View style={{ width: 32, paddingLeft: 10, alignItems: 'center', justifyContent: 'center' }}>
            <Icon name={iconName} size={size} color={color} />
          </View>
        );
      };
    };

..
..
..

<GiftedForm.TextInputWidget
          name='emailAddress' // mandatory
          title='Email address'
          placeholder='example@nomads.ly'
          keyboardType='email-address'
          clearButtonMode='while-editing'
          customValidationView={getValidationRenderer('ios-mail', Colors.blue10, false)}
/>