'Add a user' is the correct form in English. Use of 'a' or 'an' are not determined by spelling, but pronunciation. Any word which sounds like it begins with a vowel (it may or may not actually begin with a vowel) will take 'an' and any word which begins with sound of a consonant will take 'a' as the preceding article.
Enh: Added select2 dropdown for language selection in account and admin settings
Enh: Added data-ui-select2 addition for simple select2 dropdowns
Fix: Don't apply js additions if there was no matching element
