Fixes logging from controllers (fixes #36)

Raisin::API exports `app` which has `log` method registered by a
logging plugin.

README.md

@@ -650,11 +650,15 @@ Or use [Raisin::Logger](https://metacpan.org/pod/Raisin::Logger) with a `fallbac
 
     plugin 'Logger', fallback => 1;
 
-Exports `log` subroutine.
+The plugin registers a `log` subroutine to [Raisin](https://metacpan.org/pod/Raisin). Below are examples of
+how to use it.
 
-    log(debug => 'Debug!');
-    log(warn => 'Warn!');
-    log(error => 'Error!');
+    app->log(debug => 'Debug!');
+    app->log(warn => 'Warn!');
+    app->log(error => 'Error!');
+
+`app` is a [Raisin](https://metacpan.org/pod/Raisin) instance, so you can use `$self` instead of `app` where
+it is possible.
 
 See [Raisin::Plugin::Logger](https://metacpan.org/pod/Raisin::Plugin::Logger).
 

examples/sample-app/lib/RESTApp.pm

@@ -18,6 +18,8 @@ middleware 'CrossOrigin',
 
 plugin 'Logger', outputs => [['Screen', min_level => 'debug']];
 
+app->log(debug => 'Loading Raisin...');
+
 swagger_setup(
     title => 'Users & hosts API',
     description => 'An example of API documentation.',

lib/Raisin.pm

@@ -993,11 +993,15 @@ Or use L<Raisin::Logger> with a C<fallback> option:
 
     plugin 'Logger', fallback => 1;
 
-Exports C<log> subroutine.
+The plugin registers a C<log> subroutine to L<Raisin>. Below are examples of
+how to use it.
 
-    log(debug => 'Debug!');
-    log(warn => 'Warn!');
-    log(error => 'Error!');
+    app->log(debug => 'Debug!');
+    app->log(warn => 'Warn!');
+    app->log(error => 'Error!');
+
+C<app> is a L<Raisin> instance, so you can use C<$self> instead of C<app> where
+it is possible.
 
 See L<Raisin::Plugin::Logger>.
 

lib/Raisin/API.pm

@@ -10,8 +10,12 @@ use Carp;
 use Raisin;
 use Raisin::Entity;
 
-my @APP_CONF_METHODS = qw(api_default_format api_format api_version middleware
-    mount plugin register_decoder register_encoder);
+my @APP_CONF_METHODS = qw(
+    app
+    api_default_format api_format api_version
+    middleware mount plugin
+    register_decoder register_encoder
+);
 my @APP_EXEC_METHODS = qw(new run);
 my @APP_METHODS = qw(req res param include_missing session present error);
 my @HOOKS_METHODS = qw(before before_validation after_validation after);