Fixed error with description and screenshots. Also added icons & screenshot-2

git-svn-id: https://plugins.svn.wordpress.org/simple-price-calculator-basic/trunk@998779 b8457f37-d9ea-0310-8a92-e5e31aec5664
fixed description styling error

git-svn-id: https://plugins.svn.wordpress.org/simple-price-calculator-basic/trunk@998781 b8457f37-d9ea-0310-8a92-e5e31aec5664