Revert "Added libraries rpath."

It is a bad practice to put the libraries' path inside them.

This reverts commit 088220ad.

src/CMakeLists.txt

@@ -81,7 +81,6 @@ SET_TARGET_PROPERTIES(${plugin}
    PROPERTIES
    COMPILE_FLAGS "${${PROJECT_NAME}_CXXFLAGS}"
    PREFIX ""
-   INSTALL_RPATH ${CMAKE_INSTALL_PREFIX}/lib/plugin
    LIBRARY_OUTPUT_DIRECTORY "${${PROJECT_NAME}_BINARY_DIR}/lib/plugin")
 
 INSTALL(TARGETS ${plugin}