Add tests for supported column types.
Removed empty new line in Save widget
Fix settings for Mosaic Display
Skip smallserial and bigserial tests on old postgres servers.
Use underscore for Mosaic display settings
Nicer lines in Mosaic Display
Merge pull request #118 from astaric/column-type-tests

Add tests for supported column types.
Always treat sql columns of type 'serial' as continuous variables.
Add properties X and Y to SQL tables.
Use cached values.
Simplify interface for Mosaic Display
Merge pull request #122 from tomazc/majority_learner

Majority learner missing values unit test.
Add tests.
Merge pull request #120 from janezd/mosaic_settings

Mosaic settings
Merge pull request #116 from marinkaz/master

Removed empty new line in Save widget
Expand tests.
Remove print.
Cast all numeric columns to double precision.
Fix refresh_tables() so that "Custom SQL" is always available.
Use the new context manager for execution of sql queries in owparallelgraph.