Initial Checkin of ffi-vixdisklib Gem

Gem supporting FFI binding to VMware VixDiskLib
library.  There are three layers to the binding -
the raw ffi-vixdisklib accessed by requiring
'ffi-vixdisklib', the API wrapper supporting memory
management of the input and output argument structures,
accessed by requiring 'ffi-vixdisklib/api_wrapper',
and the ManageIQ wrapper managing VixDiskLib connections
and disk objects, accessed by requiring 'ffi-vixdisklib/miq_wrapper'.