Added basic install target to Makefile.

Right now this only works for the non-mpic++ variety: In that case the installation procedure is 'make lib' and then 'sudo make install'. Later a flag in the Makefile, or better yet a configure script, should make sure the installation works even if mpic++ is not installed.
Merge pull request #8 from olavolav/minor_fixes

Minor fixes
Merge commit '882607919293db9511c2be0b3924d710eccd35c7' into libc++