Add method to retrieve status of Raft node.

Now it's possible to discover if a node is follower, candidate, leader, or it even hasn't joined a cluster. This information is usefull to monitor cluster state.
Typo.
Add proper includes.

Classes in forwards.hpp use boost::optional and boost::variant, so corresponding headers should be included.
Fixed RHEL6 builds.
Fixed a missing return statement.
Don't run reactor from two threads.

Each actor creates own thread and runs its reactor there. So passing one reactor to two actors is a bad idea.
Merge pull request #82 from andrusha97/raft-monitorings

Raft monitoring
Remove boost-python from BuildRequires
Merge pull request #87 from noxiouz/fix-spec

Remove boost-python from BuildRequires
Fixed building on some systems.

Now ${Boost_LIBRARIES} variable is used instead of particular Boost library names. For example, these libraries have some different names on Ubuntu Trusty and Fedora.

Conflicts:
	CMakeLists.txt
Fixed building on some systems again.

Cocaine Runtime also links with some boost libraries. I forgot to fix it in the previous commit.
Cleanup.
Blackhole logging system has been injected into cocaine.
Cleanup, p. 2.
Merge pull request #89 from 3Hren/ft-Logging

New logging system.
Merge branch 'master' of github.com:cocaine/cocaine-core
Added drain graphs in resolve results.

Locator will return drain graph for a message, along with message alias
and transition graph now. This is required for frameworks to construct
handling objects appropriately. For backward compatibility, all messages
have a 'streaming_tag' drain for now.
Initialize the max channel counter to zero.

Previously, the max channel number was uninitialized, so messages were
dropped randomly because their channel id was lower than the garbage in
the max channel counter.
No automatic channel revocations.

Sessions will drop channels only when the client has sent the last
message according to the protocol dispatch graph.
Fix building on ancient compilers.