Adapt title color of dialogues

[ChristianeMussmacher]

The font color of all dialogue titles is blue, preferable it should be changed to UNIHELD green.

Dialogues in Hoccer/ UNIHELD:

• Select attachment
• edit attachment
• decline invitation
• add contact
• delete contact
• delete group
• delete profile
• enter code
• add contact
• upload avatar

/Users/christianemussmacher/Library/Containers/com.apple.mail/Data/Library/Mail Downloads/F1A2AA99-4C69-460E-A612-2B7862222AFC/Screenshot_20170307-111621.png