Calendar colors

Few modifications to color coding:

• every flying team appointment should be in orange
• cancelled appointments should be in grey
• noshow appointments should be in red

mentioned in issue #79 (closed)

assigned to @piotr.gawron

created branch 89-calendar-colors

mentioned in merge request !37 (merged)

closed via merge request !37 (merged)

closed via commit 959b81e4

mentioned in issue #99 (closed)