eliminated unnecessary cd and failing substitution

Changing the working directory in a sub-subshell
does not change the working directory of the executing
shell.

The substitution was broken for me on _all_ my machines,
so I started looking into the business.
Adding a fix for the DISABLE_UNTRACKED_FILES_DIRTY option.
Add web-search plugin.

This plugin adds google, bing and yahoo commands to launch the default
web browser to do web search:

e.g.

    google oh-my-zsh
    bing what is zsh
Fixed recursion. Git not needed for it to work.

Avoid infinite `cd` loops under certain conditions. Try getting `.venv` from the current directory (not necessarily always using git)
Updated README and install script to point to the fork and not upstream