Add help icon for metadata

[senaarpinar]

While entering metadata for a collection, we need to display a help icon next to each selected metadata field to provide the description, example for each and a link to a wiki page.

Object model for namespaces should be updated to have fields for description, example and a url.

Get the descriptions, examples and urls from the excel sheet once #84 is done.

[senaarpinar]

help icon UI (and object model changes) has been implemented. Need to update the datatypes in the database with descriptions/examples/wiki url from the spreadsheet.