lastpass-cli - add bash and fish completion scripts

[rderik]

Added to the formula the code to install the bash and fish completion
scripts.

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[fxcoudert]

Thanks @rderik for the pull request!

[BenjaminHCCarr]

@fxcoudert @ilovezfs
I see that https://github.com/Homebrew/homebrew-core/blob/master/Formula/lastpass-cli.rb#L10 indicates a bottle rebuild: rebuild 1.
However, the formula is not automatically indicating that it needs to be updated by brew. In the old old old days we used to stick a {#ver}_1 on it to force the upgrade for users. is there no hook for rebottled builds? I had to manually brew reinstall lastpass-cli to get tab completion to install.