Add socket.tcp_connect method

 + fix regexp in socket:readline (seeks shortest line)
 + tests for .tcp_connect is example of HTTP-client
Backport tcp_connect method for sockets.

+ fix socket:readline regexp.
Merge branch 'stable' of github.com:tarantool/tarantool

Conflicts:
	src/lua/bsdsocket.lua
	test/box/bsdsocket.test
Merge branch 'master' of https://github.com/tarantool/tarantool