proposed fix for #12

[gadeynebram]

A user defines a @hidden field in the project named requiredfieldtranslations

The content matches the specified languages but provides translated labels for required field.

e.g. languages field:
1,en
2,nl

e.g. requiredfieldtranslations field:
1,Required value *
2,Verplicht veld *

Exceptions:

• If the requiredfieldtranslations field is missing then the English fields are still removed as was the case before this fix.
• If one of the languages is not specified in the requiredfieldtranslations field then the requiredlabel fields are cleared but not removed. They act as placeholders in case the user selects a different language.
• Fields that have no translations specified are not processed by the current javascript. Therefore all existing requiredlabel fields are replaced before translating the questions.