Provide the Fish function

Signed-off-by: Clement Escoffier <clement.escoffier@gmail.com>
Provides the export function

Signed-off-by: Clement Escoffier <clement.escoffier@gmail.com>
Describes the fish configuration process.

Signed-off-by: Clement Escoffier <clement.escoffier@gmail.com>
Merge pull request #46 from cescoffier/fish

Add fish shell support