Adjust for new encoding scheme, and include a challenging password, having:
- plain ascii
- url-sensitive ascii
- latin 1
- btoa-breaking (simple Chinese, and Hebrew) characters
Get non-basic multilingual plane characters working in share room
passwords.  Do so in a way that reconciles our various character set
provisions:

- Use a common javascript method for encoding usernames and passwords to
  UTF8.

- Ensure that the host setting, when changed, is converted to UTF8.  I
  believe this is in accordance with
  http://www.w3.org/International/articles/idn-and-iri/#irioverview

- Eliminate consolidation of non-basic multilingual character plane
  ("astral plane") characters.  (Apparently the server is fine with the
  expanded versions - not sure how/when I encountered problems that
  suggested otherwise.)
Merge pull request #294 from SpiderOak/issue-293-utf8-in-share-room-passwords

Issue 293 utf8 in share room passwords