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_pass_through.cpp b/occ_pass_through.cpp
index 11ef469..a53cba4 100644
--- a/occ_pass_through.cpp
+++ b/occ_pass_through.cpp
@@ -21,15 +21,16 @@
 namespace occ
 {
 
-PassThrough::PassThrough(sdbusplus::bus::bus& bus, const char* path) :
-    Iface(bus, path), path(path),
+PassThrough::PassThrough(const char* path) :
+    Iface(utils::getBus(), path), path(path),
     devicePath(OCC_DEV_PATH + std::to_string((this->path.back() - '0') + 1)),
     occInstance(this->path.back() - '0'),
     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(&PassThrough::activeStatusEvent), this,
                   std::placeholders::_1)),
-    occCmd(occInstance, bus, path)
+    occCmd(occInstance, path)
 {
     // Nothing to do.
 }