GradleRIO build.gradle changes to support VMXpi-wpilib

[kauailabs]

[It's not clear yet whether this work will be done by Jaci, or by the Kauai Labs buildmaster; this issue is created to track the dependency.]

From email from Jaci Brunning on 6/7/2018:

2. There are a few changes that will have to be made to the build.gradle. The most important change is to add your Raspberry Pi as a deploy target in the build.gradle, which follows the same sort of structure as the RoboRIO, but with a new IP address and such. There's a few internal things in GradleRIO we'll have to change as well (the deploy process to still do FRC-specific behaviour on a non-RoboRIO target). The VMX dependencies will also have to be added, but other than that it should all be pretty much the same. I'll get back to you on how exactly to go about this, but I'll need the maven repo to be alive and well before this can be done.