don't bypass the web of trust (#378)

the choice whether to use a web of trust and on which trust level is up
to the user of PGP/GPG and must not be overriden by tools that are set
on top

users can decide to ignore this safety net by setting their gpg.conf
adequately, defining an alias for `gpg --trust-model=always` or passing
the env GPG to blackbox in this way but we should not override their
preferences hardcoded

bin/_blackbox_common.sh

@@ -253,7 +253,7 @@ function encrypt_file() {
   encrypted="$2"
 
   echo "========== Encrypting: $unencrypted" >&2
-  $GPG --use-agent --yes --trust-model=always --encrypt -o "$encrypted"  $(awk '{ print "-r" $1 }' < "$BB_ADMINS") "$unencrypted" >&2
+  $GPG --use-agent --yes --encrypt -o "$encrypted"  $(awk '{ print "-r" $1 }' < "$BB_ADMINS") "$unencrypted" >&2
   echo '========== Encrypting: DONE' >&2
 }
 

pkg/crypters/gnupg/gnupg.go

@@ -106,7 +106,6 @@ func (crypt CrypterHandle) Encrypt(filename string, umask int, receivers []strin
 	a := []string{
 		"--use-agent",
 		"--yes",
-		"--trust-model=always",
 		"--encrypt",
 		"-o", encrypted,
 	}