Cleanup
Replace deprecated OUTPUT_PATH variables with OUTPUT_DIRECTORY equivalents

This time do not use per-config variables, but let CMake handle them.

DLLs are considered "RUNTIME" on windows, and therefore, from this patch,
they will end in the "bin" directory. Therefore install commands are update
to reflect this change.
Fix Qt5 executables and plugins

The path is now different for build-tree and install-tree for multi
config generators, but the executables now import both paths.
Merge pull request #234 from drdanz/OUTPUT_DIRECTORY

Update variables and fix Qt5 executables