Change "created by" to "uploaded by" in Clowder

When the user uploads a dataset, it is shown as "Created By" at the top. This information is not part of metadata that gets transmitted with OAI-ORE maps. Creators of the dataset still need to be added as part of dropdown list metadata. This will create confusion as users may not be able to distinguish between "created by" and "dataset creators".

To make the distinction even clearer, we could add a tip after "Uploaded by" that says "To specify authors of the dataset, please select "creator" in the metadata list below and add authors' names and IDs".

See also https://opensource.ncsa.illinois.edu/jira/browse/CATS-448