gnupg2 is designed coexist with gnupg 1.x. The formula contains a patch
to keep things like documentation and language data from conflicting
with gnupg 1.x by namespacing everything as 'gnupg2'.
gpg-agent is currently an external package in Homebrew, as it can also
be used with gnupg 1.x; so in the formula we disable building the agent
and declare a dependency on it instead.
Signed-off-by: Jack Nagel <jacknagel@gmail.com>