enhanced parsing of binaries on Windows when installing LR

included `pe-parser` module (no longer `objdump.exe`, which is removed), updated installer to check architecture (32/64) interpreter was compiled for (instead of system architecture). Runtime detection should now also properly work on 64bit binaries.

@moteus: It now uses the architecture the interpreter was compiled for (32/64bit). Can you give this a try? see https://github.com/keplerproject/luarocks/issues/161#issuecomment-25866704 
@ignacio: Can you test again against a 64bit Lua interpreter that failed previously. See https://github.com/keplerproject/luarocks/pull/130#issuecomment-17373816

and obviously everybody else is encouraged to test as well...