Update README with Linux flavor statement

The GlenJarvis.com website will be deployed on AWS and with the CentOS branded
Amazon Linux AMI. To avoid differences in Linux flavors and thus potential
bugs/contention, clarification is made for collaborators. For example, there
should be no Debian package management commands used as this is not targetted
to run on Debian.
Add configuration script for user convenience

Script `configure.py` will link pem key to correct location and do extra error
checking to save the user headaches later
Fix stale comments on configure() function
Update check_pem_permissions documentation per peer review

If `check_pem_permissions` were taken out of context and used elsewhere, the
preconditions to the function would not be clearly understood. Update the
documentation `check_pem_permissions` docstring explictly stating the
precondition.
Merge pull request #10 from glenjarvis/feature/clarify_for_sharing_with_other_engineers

Feature/clarify for sharing with other engineers