NEW Making widgets dependency optional
Fixed BlogHolder->providePermissions() declaration

Placed on controller instead of model. Thanks @tractorcow
for pointing this out.
API Moved "SideBar" widget relation to "widgets" module

Removed BlogTreeExtension in favour of the new WidgetPageExtension
in the "widgets module". Use the following code to update:

Object::add_extension('BlogTree', 'WidgetPageExtension');
Object::add_extension('BlogEntry', 'WidgetPageExtension');

The template placeholder has been renamed from $SideBar to
$SideBarView. In case you're overriding blog templates,
please adjust accordingly.

This change means that widgets can theoretically be applied
to individual blog entries as well, since they need the
"SideBar" relationship as well. In practice, this defaults
to "InheritSideBar" though, which pulls them from the BlogHolder as usual.
Merge pull request #83 from silverstripe/pulls/widget-decoupling

API Moved "SideBar" widget relation to "widgets" module
Fixed BlogEntryForm saving regression from df544e01f

Was saving to live before overwriting with draft again.
Since no write to draft ocurred before, this broke
the publish() call - e.g. visible by the test breakage
in BlogHolderFunctionalTest.
Merge remote-tracking branch 'upstream/0.6'