add es6-promise shim

It is expected that support for promises will be available in whatever
environment liza is run.  Here, we're adding a shim for the sake of testing
in ancient environments.

It's almost as if I'm stuck using an ancient environment somewhere...*cough*

Makefile.am

@@ -18,7 +18,8 @@
 #  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 ##
 
-path_src = $(top_builddir)/src
+path_src  = $(top_builddir)/src
+path_test = $(top_builddir)/test
 
 namespaces=$(shell find src -type d)
 nsindex=$(addsuffix /index.js, $(namespaces))
@@ -37,6 +38,6 @@ modindex: $(nsindex)
 test: check
 check:
 	@PATH="$(PATH):$(CURDIR)/node_modules/mocha/bin" \
-		mocha --recursive $(TESTARGS)
+		mocha --require $(path_test)/pre.js --recursive $(TESTARGS)
 
 FORCE:

package.json.in

@@ -19,7 +19,8 @@
   },
   "devDependencies": {
     "chai":   ">=1.9.1",
-    "mocha":  ">=1.18.2"
+    "mocha":  ">=1.18.2",
+    "es6-promise": "~3"
   },
 
   "licenses": [

test/pre.js

@@ -0,0 +1,23 @@
+/**
+ * Pre-test setup
+ *
+ *  Copyright (C) 2016 LoVullo Associates, Inc.
+ *
+ *  This file is part of liza.
+ *
+ *  liza is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+// polyfill for ancient environments
+require( 'es6-promise' ).polyfill();