Update Discord badge colors (#3065)

* Update Discord badge colors

The badge colors were blue, while you can use color codes (like 738bd7 used here). This changes the discord badge colors to 738bd7.

* Change to official Discord Blurple

based on https://discordapp.com/branding

README.md

@@ -20,12 +20,12 @@ FAQ
 Contributing
 =========
 - Please read the [coding style and Commit/Pull Request guidelines](https://github.com/HearthSim/Hearthstone-Deck-Tracker/blob/master/CONTRIBUTING.md).
-- [![joindeveloper#hdt](https://img.shields.io/badge/Discord-Developer%20Server-blue.svg)](https://discord.gg/CMw965f)
+- [![joindeveloper#hdt](https://img.shields.io/badge/Discord-Developer%20Server-7289da.svg)](https://discord.gg/CMw965f)
 - [![Join the chat at https://gitter.im/HearthSim/Hearthstone-Deck-Tracker](https://badges.gitter.im/Join%20Chat.svg)](https://gitter.im/HearthSim/Hearthstone-Deck-Tracker?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)  
 
 Community
 =========
-- [![Join HearthSim #hdt](https://img.shields.io/badge/Discord-Community%20Server-blue.svg)](https://discord.gg/gdYsV2y)
+- [![Join HearthSim #hdt](https://img.shields.io/badge/Discord-Community%20Server-7289da.svg)](https://discord.gg/gdYsV2y)
 - **HearthSim**: Hearthstone Deck Tracker is a [HearthSim](https://hearthsim.info) project. Come join us in #hearthsim on chat.freenode.net.
 
 Features