poco: library install dirs per RUNTIME/LIBRARY/ARCHIVE

For a unix system, this commit implies no changes by default. However, the ${LIB_SUFFIX} convention was added so the build can be configured for a red-hat style installation which uses lib64 by specifying cmake -DLIB_SUFFIX=64

For a windows build (msvc), this commit will cause the .dll files to be installed in the bin/ path; import libraries .lib are still installed in the lib/ path. Installing dlls into the bin path is preferable because dlls must be in the executable %PATH% to be found at runtime, as there is not equivalent of a separate library path as there is on unix.