Add base support for GPIO presence

This is the starting code needed to build the application.

Change-Id: I46112a222afbc057ac4fc4f8fb2b4c83822023df
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/.gitignore b/.gitignore
index 50e667c..00cb02d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -42,6 +42,7 @@
 /config.log
 /config.status
 /phosphor-gpio-monitor
+/presence/phosphor-gpio-presence
 Makefile
 .deps
 /*-libtool