CORD-1335: Support pluralization via xproto + supporting unit test

Change-Id: Ie3c0a5a3354d2846427d51c4675e53e855d25bde
diff --git a/xos/genx/tool/plurals.xtarget b/xos/genx/tool/plurals.xtarget
new file mode 100644
index 0000000..9cdd6c6
--- /dev/null
+++ b/xos/genx/tool/plurals.xtarget
@@ -0,0 +1,6 @@
+{% for m in proto.messages %}
+Model {{ m.name }}:
+{% for f in m.fields -%}
+The plural of {{ f.name}} is {{ xproto_pluralize(f) }}.
+{% endfor %}
+{%- endfor %}