update gitignore
refactor session handling and update tests
update tests, use memory db
update tests to cover exception case
Merge remote-tracking branch 'remotes/upstream/master'

Conflicts:
	skosprovider_sqlalchemy/providers.py
	tests/test_providers.py
fix compat error
manualy resolve some merge issues from original skosprovider_sqlalchemy
Merge remote-tracking branch 'remotes/upstream/master'

Conflicts:
	skosprovider_sqlalchemy/providers.py
	tests/test_providers.py
fix hung sessions
fix table locks during testing on postgresql
refactor tests, run in ful isolation
Add missing coverage report.
Merge branch 'BartSaelen-master'