Modernize the code base to C++11 standards and beyond.

Apply `clang-modernize` (based on Clang 3.6) transformations to the
codebase while making sure to support Clang>=3.4 and GCC>=4.8.

We apply the transformations in parallel to speed up the quite
time consuming process, and use our `clang-format` style file
to automatically format the code respecting our coding conventions.

We use the following self-explanatory transformations:

* AddOverride
* LoopConvert
* PassByValue
* ReplaceAutoPtr
* UseAuto
* UseNullptr

This required a `compile_commands.json` compilation database, e.g.

    ccmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_EXPORT_COMPILE_COMMANDS=1

for CMake or check Bear for a Makefile based solution (or even Ninja).

    git ls-files -x '*.cpp|*.h' | \
      xargs -I{} -P $(nproc) clang-modernize -p build -final-syntax-check -format -style=file -summary -for-compilers=clang-3.4,gcc-4.8 -include . -exclude third_party {}

Boom!

References:

* http://clang.llvm.org/extra/clang-modernize.html
* http://clang.llvm.org/extra/ModernizerUsage.html

server/data_structures/internal_datafacade.hpp

@@ -264,7 +264,7 @@ template <class EdgeDataT> class InternalDataFacade final : public BaseDataFacad
             throw osrm::exception("no names file given in ini file");
         }
 
-        ServerPaths::const_iterator paths_iterator = server_paths.find("hsgrdata");
+        auto paths_iterator = server_paths.find("hsgrdata");
         BOOST_ASSERT(server_paths.end() != paths_iterator);
         const boost::filesystem::path &hsgr_path = paths_iterator->second;
         paths_iterator = server_paths.find("timestamp");

server/http/header.hpp

@@ -37,7 +37,7 @@ struct header
 {
     // explicitly use default copy c'tor as adding move c'tor
     header &operator=(const header &other) = default;
-    header(const std::string &name, const std::string &value) : name(name), value(value) {}
+    header(std::string name, std::string value) : name(std::move(name)), value(std::move(value)) {}
     header(header &&other) : name(std::move(other.name)), value(std::move(other.value)) {}
 
     void clear()