[setup] in case of Macos 10.[7, 8, 9] the value of JAVA_HOME is overwritten

For newer darwins the value of java_home is overwritten (silently) and users have not chance to point to a valid
installation. Additionally the path to the headers from a recent openjdk (1.7u51) are Home/includes instead of Home/Headers, which is also fixed by this commit.
Tested against openjdk 1.7u51