Added fish-shell 2.x.x supports.

Signed-off-by: Rack Lin <racklin@gmail.com>
Added export alias for bourne shell compatibility.

Signed-off-by: Rack Lin <racklin@gmail.com>
Added fish-shell completions

Signed-off-by: Rack Lin <racklin@gmail.com>
Fixed fish shell completions not working issues.

Signed-off-by: Rack Lin <racklin@gmail.com>
Added `phpbrew init` install phpbrew.fish to phpbrew_home and display init messages for fish-shell.

Signed-off-by: Rack Lin <racklin@gmail.com>
Merge pull request #415 from racklin/enhancement/fish-shell

Added fish-shell 2.x supports.