Inplace volumetrics container (#13)
* Initial setup for inplace volumetrics container
* Added support for multiple ensembles and multiple input sources
* Added option to set initial response
* Remove erroneous commited file
* Added WebvizContainer parent class
* Added test
* Fixed linting
* Updated container description. Removed title
* Updated example
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* Added more readiable abbreviations for responses
* Capitalize group categories
* Unstack histogram and barchart
* Changed data source to key value pairs
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* Fixed test
* Linting and descriptions
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