Support RGB, hex values, and add known colours to DC Webmail Notifier

[Aupajo]

This PR:

• Renames send to send_data, to avoid overriding Ruby's core send method.
• Adds a colour_rgb! method (usage: colour_rgb!(255, 0, 255))
• Adds a colour_hex! method (usage: colour_hex!("00ff00"))
• Adds methods for the following colours: black, white, green, red, blue, orange, teal, yellow, pink
• Does not break the existing WebmailNotifier API (all methods before this change are still supported)

[perryn]

Hi there

Thanks for sending a pull request!

However, I'm not sure why you want to add methods that allow client code to set colour directly? Generally in blinky CI plugins call methods like (failure!, success!, warning!, etc) and it is up to the light plugin implementation to map that to a colour (or whatever). Why did you find these colour methods useful?

[Aupajo]

Oh, I'm not using this library for CI. I'm using it as a general-purpose indicator.

I've written a game using it, which flashes between colours, and a colour picker that you can choose to set the colour of the light to any hex value.