Implemented com.twosigma.beaker.chart.Color class

The new class replaces java.awt.Color.
Also removed java.swing.ImageIcon use
Fix for bug 688 - use of charting API pops up Java icon

Removed use of java.awt everywhere and replaced with an internal
implementation that replaces (most of: ColorSpaces are not implemented)
java.awt.Color functionalities.
Merge pull request #719 from twosigma/ildipo/bug-688

Ildipo/bug 688