Singleton fix

System version 0.433
modules:
Blogs 0.080
Comments 0.023
Cron 0.008
Deferred tasks 0.1.2+build-5
Disqus 1.0.1+build-2
Feedback 0.006
HybridAuth 2.1.1-cs37
OAuth2 0.032
Photo_gallery 0.020
Plupload 2.0.0-cs2
Static_pages 0.040
plugins:
Admin_default_theme 0.005
Fotorama 4.4.8-cs1
SimpleImage 2.4.0-cs1
TinyMCE 4.0.12-cs1
Various fixes.
New constant IN_ADMIN

System version 0.434
modules:
Blogs 0.080
Comments 0.023
Cron 0.008
Deferred tasks 0.1.2+build-5
Disqus 1.0.1+build-2
Feedback 0.006
HybridAuth 2.1.1-cs37
OAuth2 0.032
Photo_gallery 0.020
Plupload 2.0.0-cs2
Static_pages 0.040
plugins:
Admin_default_theme 0.005
Fotorama 4.4.8-cs1
SimpleImage 2.4.0-cs1
TinyMCE 4.0.12-cs1