Track statistics for user access

[zonca]

We can track statistics on user access both at the website level and at Globus level.

I'll investigate the 2 and write more details here.

[rpwagner]

FYI: At the website level just be cautious about privacy concerns. Since the site is statically hosted on GitHub servers the obvious solution is to use a JavaScript tracking or analytics package. As part of another project we ensured that a similar mechanism was configured to capture only a minimal amount of information and we clearly disclosed what was being captured and why. That helps to address many privacy concerns.