Add missing ending newline in install_linux.sh
Use /usr/bin/env in install_linux.sh shebang line:

  bash might not be installed in `/bin/bash', this change uses the env
program, so that bash will be searched in the current search paths.
Use sh instead of bash in install script:

  sh should be available in a lot more environments than bash, relying
only on sh will allow to build on more systems. This change remove usage
of pushd and popd as it seems to be bash specific and we can achieve the
same result (installing the dynamic library) without using those
commands.
Remove mention to linux in install script:

  The README document how to build on OS/X, and after removal of the
bash dependency we should be able to build on a lot more platforms than
only GNU/Linux.
Merge pull request #21 from tjouan/portability

Impove *nix build script