Add UCD90160 class

This class represents the UCD90160 power sequencer
chip, and provides the ability to check that chip for
voltage and PGOOD faults.

This commit just adds function stubs.

Change-Id: Iec6e83e9bcddbd476bdd86a887db08f5875f11cd
Signed-off-by: Matt Spinler <spinler@us.ibm.com>
diff --git a/.gitignore b/.gitignore
index f05e3a1..bcbfb29 100644
--- a/.gitignore
+++ b/.gitignore
@@ -15,6 +15,7 @@
 config.guess
 config.h
 config.h.in
+config.h.in~
 config.log
 config.status
 config.sub