VMware: Support more than 2 driver backends

Currently the VMware version check code only supports two types of
VMware backends, Workstation and Player. But in the near future we will
have an additional one so we need to support more. Additionally, we
discover and cache the path to the vmrun binary so we should use that
path when using the cooresponding binary from the VMware VIX SDK.
VMware: Initial VMware Fusion support

Add support for VMware Fusion in the existing VMware driver.  Connect
via the URI vmwarefusion:///session