(minor) make it clearer when easy install aborts

Technically this does not add any new information, but I'm hoping it
will help the folks just won't read what's on the screen otherwise.

The main impetus this time is git 1.7.4, which is strict about
user.email and user.name and rejects commits when those config variables
are not set.  As a result, the number of times gl-easy-install hits a
fatal error and bombs out without completing its job, has increased
drastically.

src/gl-easy-install

@@ -66,6 +66,11 @@ setup_tempdir() {
 }
 
 cleanup() {
+    [ $? -eq 0 ] || {
+        printf "\n\n\t\t**ABORTED**\n\n"
+        printf "Please check messages above carefully, fix whatever is needed, and try again.\n"
+        printf "Note that the problem may be on the server, not necessarily on the client.\n\n"
+    }
     rm -rf $tmpgli
 }