CSP browser client defaults to utf8 encoding

All the CSP server stuff defaults to _utf8_ encoding - this seems to be the
only instance defaulting to _plain_. Avoids issue trying to decode on server
when input is not encoded.

Resolves #63. However, it is recommended that std.utf8.decode does not mix
deprecated escape/unescape with encodeURIComponent/decodeURIComponent.
Merge pull request #64 from gameclosure/fix-default-browser-csp-client-encoding

CSP browser client defaults to utf8 encoding