RMB cache path is not compatible with Windows

[scottyeager]

The way we form this RMB cache path creates a path that's invalid for Windows:

tfgrid-sdk-go/rmb-sdk-go/peer/twindb.go

Line 134 in 76ac3fe

path := filepath.Join(os.TempDir(), "rmb-cache", u.Host)

See here for an example of how this manifests.

What's happening is that the Host string includes a : and this is a reserved character in Windows that's not allowed in paths.

[scottyeager]

I have tested and confirmed that just swapping any : for - in the path fixes this issue.