Github and Twitter pickers do not highlight active colour on init
When initialized with prop `color`, the Github and Twitter pickers do not highlight the active colour.

All of the other colour pickers appear to update their active colour state, highlighting the active one.

This issue can be easily reproduced in [the demo](https://casesandberg.github.io/react-color/#api-color):

- Select a colour in the Github picker (or the Twitter picker)
- Copy its hex value from any of the pickers that display it to your clipboard
- Choose a different colour by clicking any of the pickers
- Paste the copied colour from your clipboard into one of the pickers that support receiving hex values

Results:

- Twitter does not update its active colour state
- Github does not update its active colour state
- Circle **does** update its active colour state (as do all the others)

Expected results (when receiving one of its included colours):

- Github picker has the 2px white outline 
- Twitter picker has the active/hover state
