Update cliprz_system/functions/datetime.functions.php

Fixing Months Bug 
the bug : 
echo c_short_month("Cliprz");
The Bug Result will be 
Clip
The Fixing is 
an array of months if it's a valid Month and exist in $months array it will be shorten else than that it will return a Bad Month Provided
Strtolower has beed used :D
Merge pull request #6 from YoussefUSF/patch-1

Update cliprz_system/functions/datetime.functions.php