Implemented architecture detection for Windows chrome executable, so that 32-bit and 64-bit windows each have their own (hopefully correct) path.

This will break existing user settings if the user has a custom path to Chrome. Users must use the key "windows_x64" or "windows_x32" instead of "windows" in their user settings file.
Restored chrome executable path for 32-bit windows to "windows" key to maintain backwards compatibility. x64 windows uses "windows_x64".
Merge pull request #58 from ithcy/ST3

Implemented architecture detection for Windows chrome executable