Add Mixmax (j-delaney#196)

Author: Brad Vogel

README.md

@@ -235,6 +235,7 @@ Please note that it is not encouraged to blindly apply to every company on this
 | [Mind Candy](http://mindcandy.com/careers) | London, UK |
 | [MindTouch](https://mindtouch.com/about/careers) | San Diego, CA |
 | [MixBit](https://mixbit.com/jobs) | San Mateo, CA |
+| [Mixmax](https://mixmax.com/careers) | San Francisco, CA |
 | [Mixpanel](https://mixpanel.com/jobs/) | San Francisco, CA |
 | [MLab](https://mlab.com/company/) | San Francisco, CA |
 | [MongoDB](https://www.mongodb.com/careers) | New York, NY; Palo Alto, CA |