* Adding dropdown to DatasourceControl and ability to change datasource
* Style fixes
* Adding unit tests for datasource/get endpoint
* Fixing issue with dropdown overflow and style changes
* Fixing issues rebasing metadata button and fixing sort for datasource with no name
* [utils] gathering/refactoring into a "utils/" folder
Moving current utils.py into utils/core.py and moving other *util*
modules under this new "utils/" as well.
Following steps include eroding at "utils/core.py" and breaking it down
into smaller modules.
* Improve tests
* Make loading examples in scope for tests
* Remove test class attrs examples_loaded and requires_examples