Multi-service client

[nairiboo]

Right now the Hypothesis javascript client implementation can only authenticate to a single annotation service at a time— the primary Hypothesis service.

We want to expand this so that the client can authenticate to many services simultaneously, some that we might manage, some that others might host. Note that this authentication isn’t related (necessarily) to the content that the user is annotating, but rather to the identity by which they are annotating with.

By supporting multiple annotation services, a user could be a member of a public annotation service, a private, company confidential annotation service, and perhaps another industry specific annotation service. On any given document, they could decide which of those services they wanted to make their annotation with, or discover which of those services had relevant annotations for them to read.