Fix key list views in main key view

Since the views are being reused, a revoked key might set the text
color of a view and when the view is being reused for a non-revoked
key it is still red. So grab the default text colour and set it
explicitly when the key is not revoked.
Merge pull request #453 from thi/452-unrevoked-keys-displayed-in-red

Fix key list views in main key view