Add shortcuts for get, and update in options loader

[alexstandiford]

Currently the only way to update an option is:
underpin()->options()->get( 'option_key' )->update( $value );

Which is a bit long-winded.

It would be nice if this were possible:

underpin()->options()->update('option_key',$value);

[alexstandiford]

underpin()->options()->pluck() has been added, which is a shortcut for the pluck method.

underpin()->options()->update() has also been updated to allow both $key and $value to automatically set array-syntax items.

The problem here is the R in the CRUD at this level gets a little confusing, because you'd want to use option()->get() as a wrapper for get_option however, get() is used to get the registry item.