Turn on a bunch of warnings

Turn on as many warnings as easily possible from:
https://github.com/lefticus/cppbestpractices/blob/e73393f25a85f83fed7399d8b65cb117d00b2231/02-Use_the_Tools_Available.md#L100

Tested:
ipmitool sensor list still works

Change-Id: Ied8fa66de9fcd25e448f8048c4f8216b426b6f55
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/src/PSUSensor.cpp b/src/PSUSensor.cpp
index fdd453a..58dee54 100644
--- a/src/PSUSensor.cpp
+++ b/src/PSUSensor.cpp
@@ -97,7 +97,7 @@
             float nvalue = std::stof(response);
             responseStream.clear();
             nvalue /= sensorFactor;
-            if (nvalue != value)
+            if (static_cast<double>(nvalue) != value)
             {
                 updateValue(nvalue);
             }