Closes Homebrew/homebrew#35417.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

This clause originated in 4a36c56ac7b36904712aa472b9bd50ef1b0c80d3,
attempting to catch NameErrors raised by const_defined? calls earlier in
the method body. Those const_defined? calls have since been moved out of
the body of the begin block.

Stop rescuing NameError here, which will make true programming errors in
formulae easier to debug.

Closes Homebrew/homebrew#33219.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Since Ruby 2.1, patch releases take the form "2.x.y" rather than
"2.x.y-pnum".

Closes Homebrew/homebrew#33860.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Before fetching or installing with no args.

Closes Homebrew/homebrew#35257.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

Print out the message pointing to the Cask and/or download location too.a

Acceptable-Formulae:

* Makes the language around stable versions stricter.
* Fixes the Homebrew/Head-only lack-of-hyphen.
* Adds Homebrew/Devel-only.

Formula-Cookbook:
* Adds a link to Interesting-Taps-&-Branches.
* Fixes the Python language to match Tim’s latest guidelines.
* Adds a note on options that aren’t ` build-with? ` or `
build-without? `.

Interesting-Taps-&-Branches:
* Slightly modifies the Versions language to better match what the
repository actually ships.
* Adds Homebrew/Devel-only to the language.

Closes Homebrew/homebrew#35298.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

This reverts commit 8fe14451842dea92bca04116ba043421b4f44a6b.

Conflicts:
	Library/Homebrew/cmd/audit.rb

The bug that prompted the two relevant commits has since been addressed.

Squashed commit of the following:

commit ecca17ede8324efd1175a42300ace8e1e2df30fa
Author: Jack Nagel <jacknagel@gmail.com>
Date:   Sat Dec 27 16:16:12 2014 -0500

    Revert "Don't use pkg_version when cleaning the cache"

    This reverts commit 4d511b5169d78a5d44bbf6c36c17f0c28014a614.

commit e8935de08f6440ae1874ce523f93b19da6b68df3
Author: Jack Nagel <jacknagel@gmail.com>
Date:   Sat Dec 27 16:16:12 2014 -0500

    Revert "Fix cleanup for head-only formulae"

    This reverts commit 510267ffd314c296c0b0969dd27d130a249f16e2.