Cannot use browsh with portable firefox bin on Windows

[nickelberg]

Using:
.\browsh.exe --firefox.path "C:\Temp\firefox_portable\firefox.exe"
Results in browsh not working.

Possible reason:
Windows browsh build uses registry to get path, version and flavor of firefox as seen in:
browsh/interfacer/src/browsh/firefox_windows.go

Possible solution 1:
Add option to statically define path, version and flavor in config file or using launch parameters.

Possible solution 2:
Skip registry check altogether when "--firefox.path" parameter is used.
As for other two variables, trust user that version and flavor are optimal when he statically defines firefox binary.