Allow setting default camera app to be used on Fluxer Android

The button to take a photo inside Fluxer Android app opens the default android camera, but when the default app is disabled, the button does nothing, and one has to open the app on its own to take photos and then go back to Fluxer and send them from the gallery. It would be easier to just have Fluxer open the 3rd party app by itself.

Either make a camera inside the Fluxer app that does now require a separate app to take pictures to send to chat or allow setting which camera app Fluxer should open to take photos.