Fix GetAvailableLanguageTags()
Fix GetAvailableLanguageTags()

commit["commit"]["author"]["date"] returns an object that looks
different depending on the current object. This can cause
DateTime.Parse to fail. The better way is to let Newtonsoft.Json
do the conversion to a DateTime.

This fixes a failing test on my machine and probably also problems
on an end user's machine.

tombogle/libpalaso,ermshiperete/libpalaso,tombogle/libpalaso,andrew-polk/libpalaso,ddaspit/libpalaso,glasseyes/libpalaso,tombogle/libpalaso,glasseyes/libpalaso,ddaspit/libpalaso,ermshiperete/libpalaso,andrew-polk/libpalaso,gtryus/libpalaso,sillsdev/libpalaso,sillsdev/libpalaso,ddaspit/libpalaso,andrew-polk/libpalaso,mccarthyrb/libpalaso,tombogle/libpalaso,glasseyes/libpalaso,mccarthyrb/libpalaso,mccarthyrb/libpalaso,gtryus/libpalaso,gtryus/libpalaso,gtryus/libpalaso,ermshiperete/libpalaso,sillsdev/libpalaso,andrew-polk/libpalaso,glasseyes/libpalaso,sillsdev/libpalaso,gmartin7/libpalaso,ermshiperete/libpalaso,ddaspit/libpalaso,gmartin7/libpalaso,gmartin7/libpalaso,mccarthyrb/libpalaso,gmartin7/libpalaso