Updated AJAX handling for app client

installController.php

	public function installfromweb() {
		$model = $this->getModel('install');
		$response = $model->installfromweb();

		echo new JResponseJson($response['body'], $response['message'], $response['error']);
		jexit();
	}

installModel.php

	public function installfromweb() {
		//@TODO: Construct the URL by passing along all URL vars except option & task
		$apps_dashboard = APPS_BASE_URL.'index.php?option=com_apps&view=dashboard&format=raw';
		$response = array();
		
		$http = JHttpFactory::getHttp();
		try {
			$html = $http->get($apps_dashboard);
			$response['body'] = $html->body;
			$response['message'] = '';
			$response['error'] = false;
		} catch (Exception $e) {
			header('HTTP/1.1 503 Service Temporarily Unavailable');
			header('Status: 503 Service Temporarily Unavailable');
			$response['message'] = $e->getMessage();
			$response['error'] = true;
		}
		
		return $response;
	}