File already in Hatrac, update with new filename

[jrchudy]

This PR intends to modify the fileExists check in hatrac.js for updating the content-disposition for a file that already exists (same md5 and content), except the new file has a different name.

One note about this PR is that a new logging action is being added, "upload/metadata/update". This follows a similar pattern with the existing createUploadJob that sets "upload/create" as the action. I figured "upload/update" wasn't specific enough (since we are only updating metadata, not the whole file) and in this case we are "updating" existing content rather than creating something new.

For documentation, where should this "action" be added? I didn't see our other action for upload in the Action List spreadsheet.

[jrchudy]

@RFSH I've updated the code to make the change you suggested. It makes sense to update the content-disposition in the fileExists function in hatrac.js since chaise won't act on this any differently. We aren't planning on communicating to the user that a file has metadata updated instead of a file being uploaded in the UI, so there's no need to separate these steps.

One note I should have mentioned before is about the logging. I updated the main body above to comment about the added log action and if we should go with what I proposed or if there is a better phrase to use.

[RFSH]

If contextHeaderParams wasn't passed to this function, line 417-423 would create it. So this if statement is pointless and this code will always use the same action for both requests. Instead you should assume contextHeaderParams is available here and do

contextHeaderParams.action = 'upload/metadata/update';

So

...

var data = "filename*=UTF-8''" + self.file.name.replace(FILENAME_REGEXP, '_');

contextHeaderParams.action = 'upload/metadata/update';
var config = {
    headers: _generateContextHeader(contextHeaderParams)
};
config.headers['content-type'] = 'text/plain';

...

[RFSH]

I manually tested uploading on chaise and ran the unit test cases. Everything works as epcted.

The changes overall look good and I just asked for a small change related to how the logging is done.