Remove the requirement of 'Parallels Virtualization SDK' for end users

There is added the usage of `libprl_sdk.5.dylib` from Parallels Desktop bundle and also `SdkWrap.h`.

So, it means that the end user of `prl-utils` will not have to install "Parallels Virtualization SDK" packege, it will be required only for compilation.

Thanks to @racktear for help. 

@rickard-von-essen, Is it possible to distribute the pre-built `prl-utils` via homebrew?