Merge pull request #37 from sanger/next_release

Aliquot model support
Merge pull request #39 from sanger/next_release

Hot fix
Add indices to aliquots.
Merge pull request #40 from brjones/add_indices_to_aliquots

Add indices to aliquots
Merge pull request #42 from sanger/next_release

Next release
Merge remote-tracking branch 'origin/next_release' into production

Conflicts:
	db/schema.rb
[#34500811] Add remove_x_and_autosomes field to studies
Merge pull request #51 from mattdenner/34500811__remove_x_and_autosomes__field_causes_study_insertion_to_fail

[#34500811] Add remove_x_and_autosomes field to studies
[#34510157] Remove indexes that have appeared magically
Merge pull request #52 from mattdenner/34510157_remove_indices_that_have_snuck_in_from_warehouse_2

[#34510157] Remove indexes that have appeared magically
[#34792267] Only update users on new study record
Merge pull request #53 from mattdenner/34792267_users_are_not_being_broadcast_reliably_for_studies

[#34792267] Only update users on new study record
[#38165671] Deactivate deadlettering if required
Merge pull request #54 from mattdenner/38165671_disable_deadlettering_if_the_environment_does_not_need_it

[#38165671] Deactivate deadlettering if required
[#38269813] Force asset link relations to be non-null
Merge pull request #55 from mattdenner/38269813_asset_links_are_appearing_with_null_relations

[#38269813] Force asset link relations to be non-null
[#38269813] Needed to swap the last two migrations
Merge pull request #56 from mattdenner/38269813_asset_links_are_appearing_with_null_relations

[#38269813] Needed to swap the last two migrations
[#39854457] Add index on sanger_sample_id
Added convenience method to delete records correctly