Tab name issue

Set a tab name to a corresponding file name in NWK. Leave setting to workspace name in a simple browser.

These tasks are the same:
[REACH-96 File names should appear in workspace tab upon save in nwk](http://adsk-oss.myjetbrains.com/youtrack/issue/REACH-96)
[REACH-107 Workspace tabs should read the filename in nwk](http://adsk-oss.myjetbrains.com/youtrack/issue/REACH-107)
if no `path` is passed it means removing saved path