The New User Management

Some of the known bugs at the moment : 

- [ ] Chosen is removed, multiselect is in as we discussed in the dev meetup but data binding for multiselect for group / sub admin selection to be ported.
- [ ] Avatars : - Once, @Kondou-ger PR gets into core, I will merge core into mine. I have defined avatars, just the libraries need to load up.
- [ ] LDAP and Password Retrieval : The PHP part I am completely unaware of, @blizzz some help here, please? 
- [ ] General PHP Cleanup : PHP hasn't been touched much in the Users Management, I am sure there is some clean up required. ( some help : @DeepDiver1975 )
- [ ] Ajaxifying everything : Group Addition, Default and User Storage works on Page refresh. Need some @Raydiation  here. ;)
- [ ] Minor Routing Fixes for SubAdmin / Everyone.
- [x] Some CSS has to be done as per the old User Management. (cc @jancborchardt, @owncloud/designers )
- [x] Quota for Unlimited Default Storage / Custom Storage is still buggy. (even in master)