* react: using prop-types package to fix deprecated React.PropTypes property warning
https://facebook.github.io/react/warnings/dont-call-proptypes.html
* removing babel devDependency because has been deprecated in favor of babel-cli
this fixes a warning during `npm install`:
```
npm WARN deprecated babel@6.23.0:
In 6.x, the babel package has been deprecated in favor of babel-cli.
Check https://opencollective.com/babel to support the Babel maintainers
```
* js: setting ExploreActionButtons.queryEndpoint PropType as required
because it's required in the child component DisplayQueryButton
* js(tests): using object in expandedSlices prop type of SliceCell tests
* js(tests): adding required props to SqlEditor mockedProps
* js(tests): adding required prop editorHeight to TabbedSqlEditors mockedProps
* js: removing unused moments dependency