Merge latest comma updates

Squashed commit of the following:

commit 737f2ac
Author: jfrux <joshua@swodev.com>
Date:   Thu Feb 28 11:13:07 2019 -0800

    Updates splash image with newer UI for README (commaai#543)

commit f020361
Author: Nigel Armstrong <legonigel@users.noreply.github.com>
Date:   Mon Feb 25 10:43:56 2019 -0800

    .gitignore visiond (commaai#539)

commit 8b7dfb6
Author: Drew Hintz <pushespretn@gmail.com>
Date:   Fri Feb 22 12:48:33 2019 -0800

    remove Pacifica 2019 from supported car list (commaai#538)

    Although there's a fingerprint and LKAS constant for the 2019 Pacifica, it doesn't work well enough that I'd consider it supported.

    P.S. I have an idea for how to support all Chrysler with one code base, even those I've never looked at. Forward can0 to the stock LKAS (can2) so that the stock LKAS is active. Then read the stock LKAS messages on can2 to both get the vehicle's LKAS constant, any status messages, and perhaps a more reliable counter. I'll try to code it up this weekend.

.gitignore

@@ -25,6 +25,7 @@ clcache
 
 board/obj/
 selfdrive/boardd/boardd
+selfdrive/visiond/visiond
 selfdrive/logcatd/logcatd
 selfdrive/proclogd/proclogd
 selfdrive/ui/ui