Remove triple brackets in bbmustache templates

Issues formerly were avoided by quoting atoms. Unquoting them created
unbalanced tags (`{{{name}}`) which were mistakes. This patch inserts
spaces to unconfused bbmustache.

priv/templates/otp_app.app.src

@@ -2,7 +2,7 @@
  [{description, "{{desc}}"},
   {vsn, "0.1.0"},
   {registered, []},
-  {mod, {{{name}}_app, []}},
+  {mod, { {{name}}_app, []}},
   {applications,
    [kernel,
     stdlib

priv/templates/relx_rebar.config

@@ -1,7 +1,7 @@
 {erl_opts, [debug_info]}.
 {deps, []}.
 
-{relx, [{release, {{{name}}, "0.1.0"},
+{relx, [{release, { {{name}}, "0.1.0" },
          [{{name}},
           sasl]},
 

priv/templates/sys.config

@@ -1,3 +1,3 @@
 [
-  {{{name}}, []}
+  { {{name}}, []}
 ].