Fix compilation errors on OS X 10.9 Mavericks.

On OS X 10.9, it looks like Clang is used by default, it does not look for
g++ 4.2 TR1 headers.
Merge pull request #1 from tetsuok/fix-compile-error-osx10.9

Fix compilation errors on OS X 10.9 Mavericks.
Made README file more github friendly.
Include the OS X specific header to use the OS specific macros.

The commit 2baa370 assumed that the macros for checking whether the user
compiles on OS X 10.9 are defined, but it was wrong because the header
which defines the macros was not included. This commit fixes this issue.
Merge pull request #2 from tetsuok/github-markdown-friendly

Made README file more github friendly.
Merge pull request #3 from tetsuok/fix-osx-mavericks-build

Include the OS X specific header to use the OS specific macros.