Merge branch 'txn' into 'master'

API.md

DATAMODEL.md

README.md

actions.go

actions_test.go

audit.go

backend/composite_values.go

backend/diff.go

backend/model.go

backend/model_test.go

backend/resources.go

backend/resources_test.go

backend/testdata/base.ldif

backend/testdata/test1.ldif

backend/testdata/test2.ldif

backend/tx.go

backend/util.go

cmd/accountserver/main.go

config.go

encryption.go