moved world plugin loader into own package

README.md

gazebo_state_plugins/CMakeLists.txt

gazebo_state_plugins/package.xml

...o_test_tools/launch/gazebo_fake_object_recognition.launch

gazebo_world_plugin_loader/CMakeLists.txt

...bo_world_plugin_loader/config/WorldPluginsTemplate.config

...r/include/gazebo_world_plugin_loader/GazeboPluginLoader.h

..._world_plugin_loader/launch/plugin_loader_template.launch

gazebo_world_plugin_loader/package.xml

gazebo_world_plugin_loader/src/GazeboPluginLoader.cpp