[BUG] Prevent scale less than the image dimensions

To Do First

• Did you try latest release? yes
• Did you look for existing matching issues? yes

Software Package Version:
1.2.1

Describe the bug
The images shouldn't move up and down or shouldnt be scaled to the smallest dimension possible. It should stay intact and should only be zoomed from initial dimensions. Please check facebook's app implementation for the reference.

Screenshots

Version (please complete the following information):

• Device: Oneplus3
• Android: 9
• react-native: 0.59.10
• react: 16.8.3

Additional context
Here is the code snippet

<SmartGallery
	images={images}
	onPageSelected={index => this.setState({ index })}
	index={index}
	loadMinimalLoader={<ActivityIndicator color="#fff" />}
/>

@Luehang please check