CORE: allow mail validation only in 6 hour window

- Allow to validate new email address only inside 6 hours window
  from moment of request creation.
- Constant (in hours) can be changed in the future.
GUI: incremental update to user detail page

- Updated design and behavior of ResourcesSettings tab
  (used to change shell etc.)
- Allow to exclude user from mailing lists.
- Updated SelfTabs location (breadcrumbs).
- Allow to set default when user changes shell on resource/facility
  (it is done by deleting value of user_facility:def:shell attribute).
- Display membership status and expiration date on SelfVos tab
  (perunadmin can change both from here).
- Updated select identity tab.
- Display notice if preferred mail change is pending (using local storage)
  and display notice, about need to validate new email when user
  types in textbox.
CORE: fixes for mail validation link

- Mail validation link now respect original rpc authz
  /perun-rpc-krb/  ->  /perun-gui-krb/
  /perun-rpc-fed/  ->  /perun-gui-fed/
  /perun-rpc-cert/ ->  /perun-gui-cert/
  any other path   ->  /perun-gui/

- Mail validation time window is taken from perun.properties
  now with fallback in source code (6 hours).
  This will make any deployment specific changes easier than
  change source code every time.

Following entry must be added to perun.properties before
accepting changes in this commit:

perun.mailchange.validationWindow = [value]

where [value] is number representing hours.