initial TriggerVersionField implementation
Merge branch 'release/0.6' into develop
open 0.7
renamed RevisionMetaInfo class attribute _revisionmetainfo
renamed _revisionmetainfo class attribute as _concurrencymeta
renamed RevisionMetaInfo as ConcurrencyOptions
per model ConcurrencyMeta
rename ConcurrencyOptions.field as _field
rename ConcurrencyOptions.versioned_save as _versioned_save
rename ConcurrencyOptions.manually as _manually
add test for ConcurrencyMeta
update Makefile to print python version
add tox to requirements.pip
Merge branch 'feature/custom_revisionmetainfo' into develop
fixes Makefile
rename TestModelWithCustomRevisionMetaInfo as TestModelWithCustomOptions

see https://code.djangoproject.com/ticket/8548
fixes django 1.7 deprecation using modelform_factory
trying to fix tox starnge issue
extends travis matrix
removes unuseful CREATE DATABASE from Makefile