BUG/MEDIUM: http: fix "http-request reject" when not final

BUG/MEDIUM: http: fix "http-request reject" when not final

When "http-request reject" was introduced in 1.8 with commit 53275e8b0
("MINOR: http: implement the "http-request reject" rule"), it was already
broken. The code mentions "it always returns ACT_RET_STOP" and obviously
a gross copy-paste made it ACT_RET_CONT. If the rule is the last one it
properly blocks, but if not the last one it gets ignored, as can be seen
with this simple configuration :

    frontend f1
        bind :8011
        mode http
        http-request reject
        http-request redirect location /

This trivial fix must be backported to 1.9 and 1.8. It is tracked by
github issue #107.