Pkgmgr's wgt backendlib - fixing name locale for package

Pkgmgr's wgt backendlib - fixing name locale for package

[Issue#]       LINUXWRT-792 / WGL-406
[Bug]          Locale isn't correctly dipatched
[Cause]        Lookup should be done without subtags too
               (that wasn't fixed when writing LocalisationTagsSingleton).
[Solution]     Use code from localisation module
[Verification] Try to install widget ta-de-004.wgt (located in wrt-extra)
               from myfiles app (copy file to /opt/usr/media/Others/).
               Displayed widget name in popup should be "PASS".

Change-Id: I4468619e441f32f1d744bba4eba08a8579fbe403