uhttp: update to latest version

uhttp: update to latest version

3fd58e9 2017-08-19 uhttpd: add manifest support
88c0b4b 2017-07-09 file: fix basic auth regression
99957f6 2017-07-02 file: remove unused "auth" member from struct
path_info
c0a569d 2017-07-02 proc: expose HTTP_AUTH_USER and HTTP_AUTH_PASS
ad93be7 2017-07-02 auth: store parsed username and password
fa51d7f 2017-07-02 proc: do not declare empty process variables
a8bf9c0 2017-01-26 uhttpd: Add TCP_FASTOPEN support
e6cfc91 2016-10-25 lua: ensure that PATH_INFO starts with a slash

Signed-off-by: Adrian Panella <ianchi74@outlook.com>