CollectionProxy#new doesn't need method_missing
Merge pull request #301 from projecthydra/collection_new

CollectionProxy#new doesn't need method_missing
Add scoping. Remove metaprogramming.

This brings ActiveFedora into parity with a more recent version of
ActiveRecord
Merge pull request #302 from projecthydra/scoping

add scoping. Remove metaprogramming.
Added #select to Relation
Remove unused delegates. Simplify method_missing logic
Use explicit delegations
This makes it easier to see what the documentation refers to.

It also means that we are not doing unnecessary work for delegations
that have no args / splats / block / etc.

Same as rails/rails@26d3e32
Merge pull request #303 from projecthydra/relation_select

Added #select to Relation
Merge pull request #304 from projecthydra/remove_cruft

Remove unused delegates. Simplify method_missing logic
Merge pull request #305 from projecthydra/explicit_delegation

Use explicit delegations
Add destroy_all on a collection association
Merge pull request #306 from projecthydra/collection_destroy_all

Add destroy_all on a collection association
Move query methods onto the relation instead of the class.

This will enable us to start chaining relations together like this:

```ruby
Library.find('test:123').books.where(author:
'Salinger').find('test:231')
```
(this doesn't yet work, but this reorganization is prerequisite for that
functionality)
Fix ActiveFedora under Ruby 2.1.
It was primarily broken because we were using `and_call_original` from
rspec-mocks

see: https://bugs.ruby-lang.org/issues/9315
Added #find() on a collection relation
Merge pull request #307 from projecthydra/query_on_relation

Move query methods onto the relation instead of the class.
Merge pull request #310 from projecthydra/fix_2.1

Fix ActiveFedora under Ruby 2.1.
Ensure that dsid and type are provided to has_metadata. Fixes #309
Accept a symbol as the datastream property for has_attributes. Fixes #308
Merge pull request #311 from projecthydra/find_on_relation

Added #find() on a collection relation