Boost_FOUND is always TRUE

No need to test Boost_FOUND variable because `find_package(Boost ...)`
has REQUIRED suboption
Build fix

Add missing `include <string>`
Fix compiler warnings

Do not definee NETWORK_ENABLE_LOGGING if already defined
Nice misprint
Merge pull request #368 from ruslo/nice.misprint

Nice misprint
Merge pull request #367 from ruslo/define.warnings

Fix compiler warnings
Merge pull request #366 from ruslo/include.string

Build fix
Merge pull request #365 from ruslo/boost.found

Boost_FOUND is always TRUE
Merge remote-tracking branch 'upstream/master'