Revert "Add docker plugin to debian/control."

This reverts commit 8a37bfc0b035c7e0f9507e2350a25a926b8627f1.
Fix connect timeout in docker plugin.

Docker client connects socket to the docker itself, this is not a work of curl. So setting of timeouts in curl is useless. I have implemented connect timeout via boost::asio timer, which stops event loop.
Remove debug logging.
Check if an asynchronous operation is aborted.

Handler of asynchronous operation mustn't perform any work, if it was aborted.
Merge branch 'v0.11' of github.com:cocaine/cocaine-plugins into v0.11

Conflicts:
	debian/control