Added a percentReszie() method

[abhimanyu003]

Added percentReszie() method to quickly increase or decrease the image size to given percent.

If want to increase the size use positive integer. If want to decrease the size use negative integer.

Example uses:

Image::open()->percentReszie(50)->html('Re-sized to 50 percent')

Image::open()->percentReszie(-50)->html('Re-sized to negative 50 percent')

[Gregwar]

Hello, this can already be done by:

$image->resize('50%')

[abhimanyu003]

Shh didn't notice that, I think language need to little clear for this.
0% == original image
50% == increase the image by 50%
-50% == decrease the image by 50%
This will be easier for calculations

Currently its
100% == original image
150% == increase the image by 50%