We recently started to get `The continuation token provided is incorrect` error
while fetching the list of backups from blob storage. Upon closer inspection, I
realized that the continuation_token was being escaped twice, which means if it
has `=` sign in it, we first escape it to `%3D` and then to `%253D`, making the
continuation_token invalid. This commit removes one of the escape calls. The
other escape is done by encode_www_form call. encode_www_form escapes few other
parameters as well, so I prefered to keep that and remove CGI.escape call which
only escapes the continuation_token.
9b856dd229