Fix NvmeSensor assert

As NvmeSensor has many async captures, deleting
the NvmeContext is not enough to make the destructor
fire, we must also manually stop all timers and
connections.

Tested: DC Cycled, assert went away

Change-Id: I64f3eab1451d73d723110a79ed5bb38419982088
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/include/NVMeSensor.hpp b/include/NVMeSensor.hpp
index 132ef29..5d2927a 100644
--- a/include/NVMeSensor.hpp
+++ b/include/NVMeSensor.hpp
@@ -33,6 +33,7 @@
     virtual ~NVMeContext();
 
     void pollNVMeDevices();
+    void close();
 
     boost::asio::deadline_timer scanTimer;
     int rootBus; // Root bus for this drive