application: introduce the Shaarli\Config namespace

Namespaces have been introduced with the REST API, and should be generalized
to the whole codebase to manage object scope and benefit from autoloading.

See:
- https://secure.php.net/manual/en/language.namespaces.php
- http://www.php-fig.org/psr/psr-4/

Signed-off-by: VirtualTam <virtualtam@flibidi.net>

tests/plugins/PluginIssoTest.php

@@ -1,4 +1,5 @@
 <?php
+use Shaarli\Config\ConfigManager;
 
 require_once 'plugins/isso/isso.php';
 

tests/plugins/PluginMarkdownTest.php

@@ -1,4 +1,5 @@
 <?php
+use Shaarli\Config\ConfigManager;
 
 /**
  * PluginMarkdownTest.php

tests/plugins/PluginPubsubhubbubTest.php

@@ -1,4 +1,5 @@
 <?php
+use Shaarli\Config\ConfigManager;
 
 require_once 'plugins/pubsubhubbub/pubsubhubbub.php';
 require_once 'application/Router.php';

tests/plugins/PluginQrcodeTest.php

@@ -1,5 +1,4 @@
 <?php
-
 /**
  * PluginQrcodeTest.php
  */

tests/plugins/PluginReadityourselfTest.php

@@ -1,4 +1,5 @@
 <?php
+use Shaarli\Config\ConfigManager;
 
 /**
  * PluginReadityourselfTest.php.php

tests/plugins/PluginWallabagTest.php

@@ -1,4 +1,5 @@
 <?php
+use Shaarli\Config\ConfigManager;
 
 /**
  * PluginWallabagTest.php.php