Add Gumstix AeroCore device

Based on the work of Andrew Smith [1], add board configuration and device
drivers to support the Gumstix AeroCore (previously Aerodroid) board [2]. The
AeroCore is an autopilot board based on a STM32F427 similar to the FMUv2.

[1] https://github.com/smithandrewc/Firmware
[2] https://store.gumstix.com/index.php/products/585/

Signed-off-by: Ash Charles <ashcharles@gmail.com>

Images/aerocore.prototype

@@ -0,0 +1,12 @@
+{
+    "board_id": 19,
+    "magic": "AeroCore",
+    "description": "Firmware for the Gumstix AeroCore board",
+    "image": "",
+    "build_time": 0,
+    "summary": "AEROCORE",
+    "version": "0.1",
+    "image_size": 0,
+    "git_identity": "",
+    "board_revision": 0
+}