Make http (curl) timeouts configurable

[pyroscope]

• Numerous timeout values compiled into the code
• Ranging from 1 min to 5 min

egrep --color=yes -RInH 'CURL.*TIME|set_timeout|m_timeout' libtorrent-0.13.6/src src/ \
| egrep -v 'sync.timeout|chunk_manager|dht_trans'

Tasks

• Add values for network.http.connect_timeout and network.http.transfer_timeout (cf. network.http.dns_cache_timeout)
• Add config that sets short values on startup, then schedules in longer ones after 2 mins or so