Increase hard timeout for getting segment headers

When we're under CPU or disk contention, doing other work
can become very slow. We want to avoid spurious errors in this situation
as this causes further retries and further contention.

One easy way to do this is to increase the time we have to finish fetching headers.

downloader/downloader/main.py

@@ -387,7 +387,7 @@ class SegmentGetter(object):
 	FETCH_RETRY = 2
 	# Headers timeout is timeout before getting the start of a response,
 	# full timeout is for the entire download and stream to disk.
-	FETCH_HEADERS_TIMEOUTS = 5, 30
+	FETCH_HEADERS_TIMEOUTS = 5, 60
 	FETCH_FULL_TIMEOUTS = 15, 240
 
 	def __init__(self, parent_logger, session, base_dir, channel, stream, segment, date):