Make `update <formula>` actually `upgrade formula` about brew

[MikeMcQuaid]

This would require adding all the argument handling/parsing for brew upgrade to brew upgrade (and the prior is written in Ruby so not Bash) which isn't really tenable.

It also means we'll need to support this perfectly forever which is an accident waiting to happen.

The command tells you what you need to do. Passing on this, sorry.

[cipri-tom]

Oh, I didn't imagine it's a big development. Sorry about my ignorance.

I imagined all is needed is to replace these three lines:

brew/Library/Homebrew/cmd/update.sh

Lines 367 to 371 in 0e9b2e3

	*)
	odie <<EOS
	This command updates brew itself, and does not take formula names.
	Use \`brew upgrade $@\` instead.
	EOS

with :

echo "Looks like you meant \`brew upgrade "${option}"\`, so running that instead"
exec brew upgrade $@