Nuke mapper- and relationship- related code :bomb:
Nuke more code and make unit spec pass
Fix travis config
Move stuff under Relation namespace to ROM namespace
Introduce ROM::Relation
Add bogus to Gemfile
Port specs to use bogus and mark some as pending
ROM::Relation should wrap graph nodes instead of axiom relations
Don't build 1.8 on travis
Don't depend on backports
Fix badge links
Revert "ROM::Relation should wrap graph nodes instead of axiom relations"

This reverts commit 8db3e9c26d1ba05ef4f68571381f97631c35353c.
Add all RA ops to ROM::Relation
Merge branch 'master' into mapper-extraction
Support passing keys when registering a relation in a repo
Use objects instead of tuples
Add pending integration spec
Replace out-dated code examples in README with a short status info
Merge branch 'master' into mapper-extraction

Conflicts:
	README.md
Rename axiom_relation => relation