iOS: Use same color for activity view as remainder of pull to refresh view.
iOS: Use same color for activity view as remainder of pull to refresh view.

The spinner is otherwise invisible on the dark theme.
samuelclay/NewsBlur,manderson23/NewsBlur,manderson23/NewsBlur,manderson23/NewsBlur,dosiecki/NewsBlur,manderson23/NewsBlur,samuelclay/NewsBlur,AlphaCluster/NewsBlur,samuelclay/NewsBlur,samuelclay/NewsBlur,samuelclay/NewsBlur,mihaip/NewsBlur,dosiecki/NewsBlur,AlphaCluster/NewsBlur,AlphaCluster/NewsBlur,AlphaCluster/NewsBlur,samuelclay/NewsBlur,dosiecki/NewsBlur,AlphaCluster/NewsBlur,dosiecki/NewsBlur,dosiecki/NewsBlur,samuelclay/NewsBlur,samuelclay/NewsBlur,manderson23/NewsBlur,manderson23/NewsBlur,AlphaCluster/NewsBlur,samuelclay/NewsBlur,mihaip/NewsBlur,mihaip/NewsBlur,dosiecki/NewsBlur,samuelclay/NewsBlur,AlphaCluster/NewsBlur,mihaip/NewsBlur,mihaip/NewsBlur,manderson23/NewsBlur,manderson23/NewsBlur,mihaip/NewsBlur,samuelclay/NewsBlur,dosiecki/NewsBlur,mihaip/NewsBlur,mihaip/NewsBlur,AlphaCluster/NewsBlur,AlphaCluster/NewsBlur,AlphaCluster/NewsBlur,manderson23/NewsBlur,dosiecki/NewsBlur,dosiecki/NewsBlur,manderson23/NewsBlur,mihaip/NewsBlur,dosiecki/NewsBlur,mihaip/NewsBlur