Fixed formatViewType 'time' for languages without meridiem

Fixed formatViewType 'time' for languages without meridiem

E.g.: bootstrap-datetimepicker.es.js has meridiem: []
that caused this error:

Uncaught TypeError: Cannot call method 'toUpperCase' of undefined

Because meridianDisplay is undefined for some languages.
Merge pull request #220 from krlos2011/master

Fixed formatViewType 'time' for languages without meridiem