Allow updating every parameter after first initialization

[SimonSimCity]

This PR fixes logbon72#116 and opens up for a new way of setting default values. The service mdcDefaultParams now returns a method, which can be invoked with an object containing all the changes you want to have as your default settings for all datetimepicker.

The service mdcDatetimePickerDefaultLocale is kept for compatibility and it's setter internally just calls:

mdcDefaultParams({ lang: localeString });

[hexadecy]

LGTM

[SimonSimCity]

You've only posted an example of how to set the default language. I would say that this way is rather deprecated in favor to the way for setting every properties default value.

The benefit with this method here is, that you can override every properties default value by injecting mdcDefaultParams and giving the properties you want to change as parameters of the first object. You can now f.e. after updating the default language, also set a new default for the button-texts with the following code:

mdcDefaultParams({ cancel-text: '', today-text: '', ok-text: '' });

Please also add this to your documentation since it shortens the HTML tag very much if you just want to have the same text everywhere - just translated to your language.

[hexadecy]

Ok, the demo now use:

mdcDefaultParams({
  lang: $scope.selectedLang,
  cancelText: $translate.instant('CANCEL'),
  todayText: $translate.instant('TODAY')
});

mdcDatetimePickerDefaultLocale will be deprecated in 1.9 with a console warning
I don't have plan to deprecate any attribute right now.