requires boost for regular make about servus

[tribal-tec]

I think it's related to not having a regex impl for gcc <= 4.8: http://stackoverflow.com/questions/12530406/is-gcc-4-8-or-earlier-buggy-about-regular-expressions

@rdumusc correct me if I'm wrong and if there's another reason for choosing boost.regex here.

[jeremybernstein]

GCC <= 4.8 isn't C++11 feature-complete anyway. GCC 4.8.1 is the first version which is: https://gcc.gnu.org/projects/cxx-status.html . It might be (IMO) better to put the boost stuff behind the SERVUS_USE_CXX03 ifdef, defining that automatically if the GCC version < 4.8.1.

[rdumusc]

correct, when I last checked std::regex support was lacking in most implementations of the standard, but we should use it if in fact possible.
Otherwise, I agree that boost::regex should be an optional dependency. It is only used for printing a compatibility warning for the URI parsing, which I am not sure is even required any longer.

[rdumusc]

Yes, implementation of std::regex_match comes with gcc 4.9 only (http://stackoverflow.com/questions/12530406/is-gcc-4-8-or-earlier-buggy-about-regular-expressions)
Added compiler guards to not include the warning when compiling without boost:
#61