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import lines compatible with goimports.

The gosocks import need to explicity name it "socks" to match what the library
does, otherwise goimports gets confused.
Add a useDeadlockDetector flag and leave it off by default.

Also run goimports everywhere.

The deadlock detector is not interacting well with the metadata downloader - where the main goroutincan be blocked for several
seconds.
Don't write heartbeats if the deadlock detector is off
Merge pull request #68 from nictuku/deadlock

Disable the deadlock detector by default