Fix missing string include error

Found by compiling on os x 10.8.5 by clang 5.0 (500.2.75)
Small refactoring for future
Do not overwrite default flags

Some flags may be setted by default, for example CMAKE_CXX_LINK_FLAGS have
'-Wl,-search_paths_first -Wl,-headerpad_max_install_names'
Fix uri_parse.cpp compilation error

Template instantiation depth need to be increased (add -ftemplate-depth=1024)
Remove unnecessary linker flags

Linker don't use '-std=c++11' flag. To link libcxx '-lc++' flag must be used.
Merge pull request #34 from ruslo/fix.build

Fix.build
Right way to link library

Looks like Xcode ignore '-lc++' in CMAKE_CXX_LINK_FLAGS,
link can be done by 'target_link_libraries' command.
Actually it is the right way to do link.
Found by building Xcode project with shared libraries.
Tested configurations: shared/static + Xcode/make
Merge pull request #35 from ruslo/xcode.build

Right way to link library
Cleaned up the awful code.
Added doxygen support (so far without comments).
Updated doxygen comments to build without warnings.
Updated doxygen comments.
Removed failing (meaningless) test.
Renamed resolve argument.