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/Thresholds.cpp b/src/Thresholds.cpp
index 3dd444d..f07f086 100644
--- a/src/Thresholds.cpp
+++ b/src/Thresholds.cpp
@@ -333,7 +333,7 @@
     const std::string& inputPath, const double& scaleFactor,
     const double& offset)
 {
-    for (auto& type : attrTypes)
+    for (const std::string& type : attrTypes)
     {
         auto attrPath = boost::replace_all_copy(inputPath, "input", type);
         std::ifstream attrFile(attrPath);