some internal refactoring
removed sql tweaking
increased test coverage
drop coverage
end of day commit
pull from staging
more specific exceptions
sql as class members
errors -> exceptions
column_types: expanded constructor
fixed get_cols-from_sql (and broken imports)
removed assertion in main code
removed naughty print statement
moved sql to class members
Merge branch 'master' into 4335-pull-from-staging

Conflicts:
	pylytics/library/connection.py
	pylytics/library/dim.py
	pylytics/library/fact.py
	pylytics/library/table.py
use create staging sql and skip tests
extracted more sql statements
Merge pull request #69 from onefinestay/4335-pull-from-staging

4335 pull from staging