Remove Boost.Filesystem v3 fix for Boost < 1.48, refactor call sites.

We needed this for Boost < 1.48, but per our Wiki on building OSRM:

> On Ubuntu 12.04 you will be limited to OSRM tag v0.3.10 because
> later versions **require Boost v1.49+** and installing this
> causes problems with libluabind-dev package.

Thus, rip it out!

To keep the commits atomic and isolated, I also refactored all call
sites that used the functionality from the portability fix.

While doing this, I also simplified the monster of around ~100 lines of
file path checking --- lambda's are awesome' use them!

References:

- http://stackoverflow.com/a/1750710
- https://github.com/Project-OSRM/osrm-backend/wiki/Building-on-Ubuntu

benchmarks/static_rtree.cpp

@@ -29,7 +29,6 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 #include "../data_structures/query_node.hpp"
 #include "../data_structures/shared_memory_vector_wrapper.hpp"
 #include "../data_structures/static_rtree.hpp"
-#include "../util/boost_filesystem_2_fix.hpp"
 #include "../data_structures/edge_based_node.hpp"
 
 #include <osrm/coordinate.hpp>