Allow building zmqpp with Microsoft Visual Studio

Changed preprocessor if directives to use || and && operators instead of words "and"/"or"
Replaced noexcept definition (if not supported) with NOEXCEPT - C++11 standard forbids defining keywords and MSVC checks that even if the keyword is not implemented (checks since version 12 (2013))
Moved socket flags to source file to prevent linker warnings about duplicate definitions
Moved inet functions into zmqpp namespace to resolve overload conflicts with system functions - windows provides an overload different only by the return value and that is forbidden in C++

Signed-off-by: Krzysztof Rapacki <shauren.dev@gmail.com>
Merge pull request #45 from Shauren/msvc_build

Allow building zmqpp with Microsoft Visual Studio