Support relative paths in unix domain file uri

[melowe]

Some reports of users expecting that the domain socket file path syntax should be able to interpret to tokens and relative paths where no root is defined to be supported. While its reasonable that URIs shouldn't use relative paths it is reasonable to say that our config could have some provision for this.

Goal
URIs with a unix: prefix should be able to handle no root slash or the use of a single dot as an implicit reference to the current working directory.

Sample pseudo uris
unix:./bogus.ipc
unix:bogus

Exception
Dont support
unix:../bogus.ipc
We don't want to have to handle navigation out of the cwd. An invalid uri exception should be raised.