gnupg2: allow installation without the suffix '2'
gnupg2: allow installation without the suffix '2'

Some programs which depend on GnuPG also depend on the binary being
installed as "gpg"; this is fine for the 1.4.x series, but for the 2.0.x
series the binaries are installed as "gpg2", etc.

Signed-off-by: Jack Nagel <43386ce32af96f5c56f2a88e458cb94cebee3751@gmail.com>

UniqMartin/homebrew-versions,coeligena/homebrew-verscustomized,jimhe/homebrew-versions,heuermh/homebrew-versions,DomT4/homebrew-versions,Ashton-W/homebrew-versions