<p>Stores a file in the file service.</p><ul><li>If <code>Owner</code> is 0, file will be stored under the authority logged in, otherwise file will be stored under the specified authority, for which the logged in user must have rights.</li><li><code>Category</code> must be a value from the 'file-category' value list.</li><li><code>Title</code> must be unique among files with same owner and category.</li><li><code>Content</code> is the Base64 encoded contents of the file to store.</li></ul><p>Returns identifier of stored file.</p><p>This operation is only valid for authorities.</p><p>Returns a list of files (identifier, title, MIME type and URL) for a given owner and category.</p><ul><li><code>Owner</code> must be an authority id.</li><li><code>Category</code> must be a value from the 'file-category' value list.</li></ul><p>This operation is valid for both applicants and authorities.</p><p>Removes a file from the file service.</p><p>This operation is only valid for authorities.</p>