Micro Deans Connectors

Here's the official page.

Polarity Convention:

• + is the male pin on the battery. 
• - is the female pin on the battery.
• + on the speed controller is the female pin (battery side)
• - on the speed controller is the male pin (battery side)

Color Convention:

• Red on batteries
• Black on ESC/charger
• Black plugs harder to get, a lot of people color them with sharpies.

Youtube overview and soldering guide.