Log Message:
Update ruby-mechanize to 2.3.

Changes:
  * Add support for the Max-Age attribute in the Set-Cookie header.
  * Added Mechanize::Download#body for compatibility with Mechanize::File when
    using Mechanize#get_file with Mechanize::Image or other Download-based
    pluggable parser.  Issue #202 by angas
  * Mechanize#max_file_buffer may be set to nil to disable creation of
    Tempfiles.
  * MetaRefresh#href is not normalized to an absolute URL, but set to the
    original value and resolved later.  It is even set to nil when the
    Refresh URL is unspecified or empty.
  * Expose ssl_version from net-http-persistent.  Patch by astera.
  * SSL parameters and proxy may now be set at any time.  Issue #194 by
    dsisnero.
  * Improved Mechanize::Page with #image_with and #images_with and
    Mechanize::Page::Image various img element attribute accessors, #caption,
    #extname, #mime_type and #fetch.  Pull request #173 by kitamomonga
  * Added MIME type parsing for content-types in Mechanize::PluggableParser
    for fine-grained parser choices.  Parsers will be chosen based on exact
    match, simplified type or media type in that order.  See
    Mechanize::PluggableParser#[]=.
  * Added Mechanize#download which downloads a response body to an IO-like or
    filename.
  * Added Mechanize::DirectorySaver which saves responses in a single
    directory.  Issue #187 by yoshie902a.
  * Added Mechanize::Page::Link#noreferrer?
  * The documentation for Mechanize::Page#search and #at now show that both
    XPath and CSS expressions are allowed.  Issue #199 by Shane Becker.
  * Mechanize now depends on net-http-persistent 2.3+.  This new version
    brings idle timeouts to help with the dreaded "too many connection \ 
resets"
    issue when POSTing to a closed connection.  Issue #123
  * SSL connections will be verified against the system certificate store by
    default.
  * Added Mechanize#retry_change_requests to allow mechanize to retry POST and
    other non-idempotent requests when you know it is safe to do so.  Issue
    #123
  * Mechanize can now stream files directly to disk without loading them into
    memory first through Mechanize::Download, a pluggable parser for
    downloading files.
  * Bug fixes.