Update to 1.0039

Upstream changes:
1.0039  2015-12-06 03:27:59 PST
    [BUG FIXES]
        - Revert the change to use the faster header builder because it breaks the legit
          Plack::Response constructor that sets HTTP::Header object directly (#541)

1.0038  2015-11-25 12:36:29 PST
    [IMPROVEMENTS]
        - Added MIME type for apk files #514 (allanwhiteford)
        - Allow passing custom formatters to Plack::Middleware::AccessLog #515 (frew)
        - Allow '0' be a valid category for log4perl middleware #523
        - Doc fix for Plack::Runner #528 (polettix)
        - Doc improvements for -R/-M command line #529 (mickeyn)
        - Bind test server explicitly on 127.0.0.1, not 0.0.0.0
        - Support single-process manager in FCGI #535 (ianburrell)
        - Optimize Plack::Response header builder #540 (kazeburo)

(wen)