/index: change 'session key' to something more understandable

[globusharris]

e.g. 'BWWC 2019 Analysis ID'.

Use handlebars for this so can change depending on deployment.

We discussed changing this to 'Company ID' and decided against this since it might signal to companies that they are identifiable by SAIL based on this ID.

[globusharris]

Should match wording to this on /manage pages as well.

[lucyq]

Should be generic and located somewhere in the config.

[globusharris]

@lucyq yep that's how I've implemented. :)

[globusharris]

Right now, handlebars only works in index.html due to server-side rendering. Working on expanding it to work for all html files now.

[lucyq]

Closed by #163