Support for repository definitions.

Add the folllowing to your template-params.xml to add dependencies
to the generated build.gradle file:
    <repository>...</repository>

Change-Id: I79c70aeef4a07d6228b762da19bd3fadaa6c381f
(cherry picked from commit b0ae7bfa5136b46cfc33d1e8604646e1728e11d6)
diff --git a/templates/base/_MODULE_/build.gradle.ftl b/templates/base/_MODULE_/build.gradle.ftl
index 4c73dd5..18c6a98 100644
--- a/templates/base/_MODULE_/build.gradle.ftl
+++ b/templates/base/_MODULE_/build.gradle.ftl
@@ -25,6 +25,14 @@
 
 apply plugin: 'android'
 
+<#if sample.repository?has_content>
+repositories {
+<#list sample.repository as rep>
+    ${rep}
+</#list>
+}
+</#if>
+
 dependencies {
 
 <#if !sample.auto_add_support_lib?has_content || sample.auto_add_support_lib == "true">