Add ./bin/console script that uses pry as irb replacement

Uses a development environment as specified in config/dev_console_env.rb
Add ability to copy contentMetadata resources from one object to another
Move console from bin to script
Add Dor::DigitalStacksService.remove_stacks_dir to remove directories from stacks by pid
Added convenience methods to the CleanupService and SearchService

-Dor::SearchService.sdr_graveyard_apo_druid finds graveyard APO by name
-Dor::CleanupService refactored so that it cleanup by pid
First pass at MergeService
Object-merge after rebase of AF6 changes
Dor::Contentable#copy_file_resources processes all secondary objects in one pass
Dor::MergeService processing re-arrangement

-One write to primary of contentMetadata
-MergeService.merge_into_primary controls merge process, but leaves details of merge to MergeService instance
Remove dev config
Handle file name collisions when merging content
Fix typos in MergeService
Contentable#copy_file_resources adds bookkeeping to copied resource nodes

-<attr> elements with name = 'mergedFromPid' and 'mergedFromResource' added to copied <resource> node in primary contentMetadata
MergeService uses bookkeeping elements when copying secondary files

-It looks at resource/attr in the primary's contentMetadata to 
determine the source pid and resource
CleanupService and DigitalStacks service use local file system access for stacks and purl operations

- Publishable#publish prunes content from Purl if object is no longer discoverable
Contentable#decomission specs
Add Dor::Config options for local stacks and purl mounts
Prep for object-merge release

- Update version of druid-tools gem
- Fix typo in MergeService
- Added script for a manual-integration test
Version bump to 4.4.0