Merge pull request #36 from andrusha97/master

"Raw" result type
Changelog bump.
Locator gateways exposed as plugins.
Simplified Adhoc gateway.
Bring back the verbosity!
Wording.
Display the gateway type on boot.
Proper gateway shutdown sequence.
Merge branch 'master' of https://github.com/cocaine/cocaine-core
Changelog bump.
Config updates.
Always set the Locator port.
Changelog fix.
Do not crash on node pruning in Locator.
Reduce log noise.

Instead of a separate log for the gateway, just stream it into the
service log for the Locator, which sounds kind of logical.
Resolve issue #26.

Update to the latest backward-cpp to hopefully fix building issues on
i386 architecture.
Changelog bump.
Tuple element extraction functor.

A handy functor to extract the specified element from a tuple, for
example to use in std::transform.
Exception simplification.

Useless io_error_t was dropped completely in favor of std::system_error,
some missed exceptions are now handled during the bootstrap.
Catch only missing cache exceptions.

Cached objects should only handle missing cache storage exceptions,
other stuff like broken caches should be propagated.