Use SSL for personal data

Currently only user name/password is encrypted using HTTP basic
encryption, but user's personal data (e.g. collections) is not
encrypted.

It is now generally accepted that all personal data should be encrypted,
and this fix applies encryption to any mblogin network requests (which
implies personal data is being loaded / saved).
Address bitmap review comment 1

This is definitely nicer code.
Address bitmap comments

Add MUSICBRAINZ_SERVERS constant and use this in options/general and to
decide SSL for mblogin webservice.