python & python3: Don't tell how to upgrade pip

Pip and setuptools can't be updated the way we write in the caveats.
This is because pip fails to remove the symlink from the
`brew --prefix`. Also we said that we don't like self-updating tools.

We will rather update the python formula, and bump the revision
(once we have the revision feature) when pip or setuptools get
updated.
python & python3: pip 1.4.1, setuptools 1.0. Yay.

Bumped pip and setuptools for python and python3.
I whish we had formula revisions already now.
But on the other hand there is no hurry as the
changes to pip/setuptools are not major.
brew reinstall: Is able to work for all formulae

... and not just installed ones. Of course, strictly speaking,
reinstalling not-yet-installed formulae makes semantically little
sense, but the big win is that we can tell people (after we have
resolved an issue) to `brew reinstall <formula>` and even if a user
has removed that formula in the meantime, reinstall will do the right
thing. Basically adding --force to uninstall. I think this makes
reinstall more robust.
Revert "brew reinstall: Is able to work for all formulae"

This reverts commit 865f763ae59fdf32f496ca416fd98117f3370f86.
brew reinstall: Is able to work for all formulae

... and not just installed ones. Of course, strictly speaking,
reinstalling not-yet-installed formulae makes semantically little
sense, but the big win is that we can tell people (after we have
resolved an issue) to `brew reinstall <formula>` and even if a user
has removed that formula in the meantime, reinstall will do the right
thing. Basically adding --force to uninstall. I think this makes
reinstall more robust.
adding reinstall to bash completion

Closes #22051.

Signed-off-by: Samuel John <github@SamuelJohn.de>