Implement remove of uri

[Grokzen]

Environment

• Phabfive version: 0.1.0
• Python version: 3.6

Proposed Functionality

Current functionality

$ phabfive diffusion
Usage:
    phabfive diffusion repo list [(active || inactive || all)] [options]
    phabfive diffusion repo create <name> [options]
    phabfive diffusion uri create (--observe || --mirror) (<credential>) <repo> <uri> [options]
    phabfive diffusion uri list <repo> [options]
    phabfive diffusion branch list <repo> [options]

Implement following behaviour

$ phabfive diffusion uri remove REPO https://foo/bar.git
Removed https://foo/bar.git from REPO

$ echo $?
0

$ phabfive diffusion uri remove REPO https://foo/non-existant.git
Unable to remove non-existant https://foo/non-existant.git from REPO

$ echo $?
0

Use Case

Enable ues to remove URI from phabricator