Stop automated redundant tor browser requests; disable network.http.connection-retry-timeout

Firefox accelerates HTTP connection timeout. See https://bugzilla.mozilla.org/show_bug.cgi?id=592284

For TorBroswer: No sense to launch parallel connection after 250ms by default, and no logic to tweak it. As long as Tor client retries stream buildings too, any "high" level timeouts makes not so much profit and probably do things much worse. Right now it overloads network and relay exits in first place with waste connection request. TBB must disable it by setting network.http.connection-retry-timeout to 0.