Remove "demo mode"

[vijay-prema]

Zotero plugin:

• Use an actual private key (how to manage it?)
• Make ExampleNanopub optional instead of hard-coded.
• Publish introduction on network, see here

Science live platform:

• Use an actual private key (how to manage it?)
• Make ExampleNanopub optional instead of hard-coded.
• Publish introduction on network, see here