Replace uses of SEE permission with READ

[Terry Jones]

We've long been uncomfortable with the SEE permission on tag values. It makes FluidDB and its documentation harder to understand and the current code that falls back to checking SEE if READ perm on a tag fails is hard to understand. But I was reluctant to just throw SEE away completely. Jamu made a good simplifying suggestion, which is to use READ instead of SEE.

If you try to access a tag that you don't have READ perm for, you just get a 401. On GET on /objects, tags that you don't have READ perm for will not be shown. So we're preserving the privacy aspect of tag values not being shown unless you have permission, but we'll do it with the READ perm instead of the SEE perm. Anywhere else that

This ticket is to replace SEE with READ in the permissions checking and to adjust all relevant tests to expect a 401 when a tag's values cannot be accessed (not a 404 when the user has SEE but not READ). The ticket does not include updating the documentation, which will be done in another ticket in order to keep branch diff size down and to allow for different reviewers to help with different things.