When adding GPG collaborator, include full fingerprint in commit message

Short key IDs are bad (https://evil32.com/)

Closes: AGWA#253

commands.cpp

@@ -1297,7 +1297,8 @@ int add_gpg_user (int argc, const char** argv)
 			std::ostringstream	commit_message_builder;
 			commit_message_builder << "Add " << collab_keys.size() << " git-crypt collaborator" << (collab_keys.size() != 1 ? "s" : "") << "\n\nNew collaborators:\n\n";
 			for (std::vector<std::pair<std::string, bool> >::const_iterator collab(collab_keys.begin()); collab != collab_keys.end(); ++collab) {
-				commit_message_builder << '\t' << gpg_shorten_fingerprint(collab->first) << ' ' << gpg_get_uid(collab->first) << '\n';
+				commit_message_builder << "    " << collab->first << '\n';
+				commit_message_builder << "        " << gpg_get_uid(collab->first) << '\n';
 			}
 
 			// git commit -m MESSAGE NEW_FILE ...

gpg.cpp

@@ -61,12 +61,6 @@ static std::string gpg_nth_column (const std::string& line, unsigned int col)
 	       line.substr(pos);
 }
 
-// given a key fingerprint, return the last 8 nibbles
-std::string gpg_shorten_fingerprint (const std::string& fingerprint)
-{
-	return fingerprint.size() == 40 ? fingerprint.substr(32) : fingerprint;
-}
-
 // given a key fingerprint, return the key's UID (e.g. "John Smith <jsmith@example.com>")
 std::string gpg_get_uid (const std::string& fingerprint)
 {

gpg.hpp

@@ -41,7 +41,6 @@ struct Gpg_error {
 	explicit Gpg_error (std::string m) : message(m) { }
 };
 
-std::string			gpg_shorten_fingerprint (const std::string& fingerprint);
 std::string			gpg_get_uid (const std::string& fingerprint);
 std::vector<std::string>	gpg_lookup_key (const std::string& query);
 std::vector<std::string>	gpg_list_secret_keys ();