Move test stubs to stubs/testcases directory

In previous version, test cases are ignored by .gitattributes
file. In line 9, we have specified tests directory will be ignored
by packagist. Then packagist evidently also excludes
"src/stubs/tests" directory which contains test cases stubs.

In this commit, we change test stub directory, so packagist
wont excludes the test stubs anymore.

.gitattributes

@@ -6,4 +6,4 @@ screenshots export-ignore
 .travis.yml export-ignore
 phpunit.xml export-ignore
 readme.md export-ignore
-tests/*/** export-ignore
+tests export-ignore

src/Generators/FeatureTestGenerator.php

@@ -24,7 +24,7 @@ class FeatureTestGenerator extends BaseGenerator
 
         $this->generateFile(
             "{$featureTestPath}/Manage{$this->modelNames['plural_model_name']}Test.php",
-            $this->getContent('tests/feature/'.$type)
+            $this->getContent('testcases/feature/'.$type)
         );
 
         $this->command->info('Manage'.$this->modelNames['plural_model_name'].'Test generated.');
@@ -77,6 +77,6 @@ class FeatureTestGenerator extends BaseGenerator
      */
     public function getBrowserKitBaseTestContent()
     {
-        return $this->files->get(__DIR__.'/../stubs/tests/browserkit-base-class.stub');
+        return $this->files->get(__DIR__.'/../stubs/testcases/browserkit-base-class.stub');
     }
 }

src/Generators/ModelPolicyTestGenerator.php

@@ -16,7 +16,7 @@ class ModelPolicyTestGenerator extends BaseGenerator
 
         $this->generateFile(
             "{$modelPolicyTestPath}/{$this->modelNames['model_name']}PolicyTest.php",
-            $this->getContent('tests/unit/model-policy')
+            $this->getContent('testcases/unit/model-policy')
         );
 
         $this->command->info($this->modelNames['model_name'].'PolicyTest (model policy) generated.');

src/Generators/ModelTestGenerator.php

@@ -16,7 +16,7 @@ class ModelTestGenerator extends BaseGenerator
 
         $this->generateFile(
             "{$unitTestPath}/{$this->modelNames['model_name']}Test.php",
-            $this->getContent('tests/unit/model')
+            $this->getContent('testcases/unit/model')
         );
 
         $this->command->info($this->modelNames['model_name'].'Test (model) generated.');