Add maintenance version (#632)

Author: swmitra

installer/win/brackets-win-install-build.xml

@@ -13,7 +13,8 @@ default="build.mul">
   <property name="product.shortname" value="Brackets"/>
   <property name="product.release.number.major" value="1"/>
   <property name="product.release.number.minor" value="12"/>
-  <property name="product.version.number" value="${product.release.number.major}.${product.release.number.minor}"/>
+  <property name="product.release.number.maint" value="1"/>
+  <property name="product.version.number" value="${product.release.number.major}.${product.release.number.minor}.${product.release.number.maint}"/>
   <property name="product.version.name" value="Release ${product.version.number}"/>
   <property name="product.fullname" value="Brackets ${product.version.name}"/>
   <property name="product.manufacturer" value="brackets.io"/>