Align category colors with SII corporate style guidelines

[cdejonghe]

1. Ensure that cheatsheet main color matches their category :

• AGILE : purple
• FRAMEWORKS : orange
• LANGUAGES : green
• PRACTICES : red
• TOOLS: blue

2. Redefine the color to follow the last corporate style guidelines :

• blue: #004278;
• light-blue: #007eb5;
• green: #097f03;
• purple: #7c08a3;
• red: #d30012;
• fuchsia: #da277a;
• orange: #D64B13;