Add windows splunk forwarder

Added logic for installing forwarder on windows.

Fixes #4 
`ENV['PROGRAMFILES']` grabs the program directory that corresponds to the current running process. When I tested it, chef was pulling back the 32 bit directory (implying that chef was 32 bit) so splunk was getting installed under the 32 bit directory even though we were choosing the 64 bit installer. I didn't take into account that the var didn't exist on 32 bit machines. Perhaps the condition should be left but the latter should call `ProgramFiles` instead of `PROGRAMFILES(x86)`?