Fix potential install problems due to failed ez_setup import.

- Setup.py now handles potential problems with ez_setup or setuptools
  imports gracefully. This should resolve any issues that users may run
  into when installing the library.
Update installation instructions.
Drop outdated install docs
Merge pull request #2 from MJJoyce/setup-install-issues

Fix potential install problems due to failed ez_setup import.
Update installation instructions.
Merge pull request #3 from MJJoyce/install-docs-update

Install docs update