Fix data-* case + add dateDaysOfWeekDisable

Fix data attribute case name. 

Separate word by hyphens in order to match with options.

Example in an input :
```
<input type=​"text" id=​"form_datepicker" name=​"form[datepicker]​" required=​"required" class=​"datepicker form-control" data-date-format=​"MM/​DD/​YYYY" data-date-language=​"fr" data-date-days-of-week-disabled=​"0,6" data-date-showtoday=​"true" data-date-pick-time=​"false" data-date-autoclose=​"false" data-date-disabled-dates=​"["04\/​02\/​2014","04\/​03\/​2014","04\/​04\/​2014"]​" data-date-time-picker=​"true" data-date-max-date="04/20/2014">​
```