let history recognize file renames as a change
recreate basic diff infrastructure
introduce Commit class for history, lazy computing of deltas
delegate commits to git
Move filepath from ontology to ontology_version
remove debug log
detect moved ontologies, save them properly
fix files controller's ontology query
don't depend on ontology_version_id to be set correctly
further steps to move path into ontology_version
use path in an ontlogy if it has no version
cosmetics
fix missing versions in factory
small fix: use each instead of map
fix basepath called on nil error
first search for path in versions, then in ontology
specify equality test on commit
fix wrong method call (method was replaced)
port history test to rspec
port diff test to rspec and fix it