Refactor D-Bus object

- The intent behind this commit is to refactor D-Bus, and abstract
  the bus, getService, getProperty and other methods into the utils
  file, and other file operations D-Bus only need to include
  uitls.hpp.

- We can also continue to add other general methods such as
  setPropery, getSubTree in the utils file in the future.

- Also, removed redundant files(occ_finder.hpp and occ_finder.cpp).

Tested: built openpower-occ-control successfully and worked.

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I53e61e30a76173c154a9f47fc122936468abbc4b
diff --git a/occ_command.cpp b/occ_command.cpp
index e9b03a9..d07c06f 100644
--- a/occ_command.cpp
+++ b/occ_command.cpp
@@ -56,13 +56,12 @@
     }
 }
 
-OccCommand::OccCommand(uint8_t instance, sdbusplus::bus::bus& bus,
-                       const char* path) :
-    occInstance(instance),
-    path(path),
+OccCommand::OccCommand(uint8_t instance, const char* path) :
+    occInstance(instance), path(path),
     devicePath(OCC_DEV_PATH + std::to_string((this->path.back() - '0') + 1)),
     activeStatusSignal(
-        bus, sdbusRule::propertiesChanged(path, "org.open_power.OCC.Status"),
+        utils::getBus(),
+        sdbusRule::propertiesChanged(path, "org.open_power.OCC.Status"),
         std::bind(std::mem_fn(&OccCommand::activeStatusEvent), this,
                   std::placeholders::_1))
 {