Use Teal Donate button across all projects

[DeniseColbert]

Buttons are in this pull request: FreeUKGen/Coordination#304

As far as I'm aware, all website colours are changing and so all four buttons need colours updating.

E4 U1 S5 C6: P 16

[DeniseColbert]

Updated title of story to reflect decision to use teal button on all websites. @AlOneill @PatReynolds teal colour has changed also: do we need to update the button to reflect this?

[PatReynolds]

Probably, in due course.

[AlOneill]

@DeniseColbert @PatReynolds the contrast required for UI elements is >=3.1:1, i.e. less stringent than the >=4.5:1 required for normal text. However, as there is a word to be read, "Donate" could do with being white on #009F98, our new teal.

The other colours are probably OK — if any of the remaining colours look wrong after the update to the button, let me know.

[DeniseColbert]

This is done so closing