Geet a java.awt.Color using the input color,
the color can by in hexadecimal notation #FFFFFF or some a predefine color
Predefined colors
black
blue
cyan
darkgray
green
grey
lightgray
magenta
orange
pink
red
yellow
white
Execute the logic of the chart and save it to the server temporaly directory
it'l return a null value if the char is null, otherwise it will the
name of the generated file with image