fix test namespacing

Author: harris21

src/Generators/stubs/feature-test.stub

@@ -1,7 +1,7 @@
 <?php
 namespace {{namespace}};
 
-use TestCase;
+use Tests\TestCase;
 use {{feature_namespace}};
 
 class {{testclass}} extends TestCase

src/Generators/stubs/job-test.stub

@@ -2,7 +2,7 @@
 namespace {{namespace}};
 
 use {{job_namespace}};
-use PHPUnit_Framework_TestCase as TestCase;
+use Tests\TestCase;
 
 class {{testclass}} extends TestCase
 {

src/Generators/stubs/operation-test.stub

@@ -1,7 +1,7 @@
 <?php
 namespace {{namespace}};
 
-use TestCase;
+use Tests\TestCase;
 use {{operation_namespace}};
 
 class {{testclass}} extends TestCase