Allow users to create database assetstore 'files'

[manthey]

Allow users to create database files.

Currently, to create a file an admin must first create an assetstore which references a specific database. The assetstore import function is used to create a Girder file that references a specific table/collection in the database with a default filter, fields, sort, limit, and format.

In addition to this, anywhere uploads are allowed we could alternately allow adding a database file.

There are a number of features that would be desired to implement this. One a basic implementation is available, some of these can become their own issues.

• [x] For the database assetstore plugin, add a settings page. This would
  • [x] have a checkbox to enable user file creation
  • [x] optionally allow any user with write privilege to add a file
  • [x] have a list of acls which specify which users are allowed to create files
  • [x] for any given acl (and the general case), allow a regex to validate the database uri. This can be used to limit the hosts, database types, etc.
• [x] Internally add a special assetstore ID that is used for user-defined files. This should be a constant so that if the plugin is disabled and reenabled no changes need to be made.
• [x] Add button on upload dialogs or where upload buttons occur to switch to the create database file dialog
• [x] Add create database file dialog. This is a similar to the current assetstore import functionality, but needs to ask for a database uri (and does not need to have the destination fields, since the upload button already has this as a context), and would only allow one table/collection at a time.
• [ ] Add a button to check access to the database uri (both in the file dialog and the create assetstore panel). This verifies that the database is reachable at the time the user is adding the file (it can be optional)
• [ ] Add a query builder to help construct fields, sort, filters. This would not support general functions at this time. See the query builder that was added to Minerva for an example of how to do this.
• [ ] Show the current default limit (try to report what it might be based on the current data with the current filters)

[manthey]

There is a WIP branch that allows a user on the web client to edit files after they have been uploaded.