Escape project root path once and only once

Fixes #256
Merge pull request #257 from TSFoster/project-root-escaping

Escape project root path once and only once
Ensure `mux copy` copies existing file over
Merge pull request #258 from TSFoster/master

Ensure `mux copy` copies existing file over
Constrain version dependencies to stop bundler warnings.
Bump to v0.6.9.
Switch to SVG badges.
Update copyright details.
[Closes #196] Clarify new and open commands.
[Closes #255] Add open to command list
Forgot that open is actually aliased.

This reverts commit 3278675fd918538943518b27e204c7c3234a21ee.
Fixes broken spec caused by #255.