Search users that should be added to usergroup

As Administrator I'd like to be able to search users that I want to add to the list of users in usergroup:

Acceptance Criteria:

1. Floating action button (FAB) should be present on the bottom right corner of users in usergroup page:
   • FAB has circle shape (blue color, size 56x56dp) and interior icon ("+") inside (white color, size 24x24dp).
   • FAB size should change from the default (56dp) to the mini size (40dp) when the screen width is 460dp or less.
   • FAB should be placed 16dp minimum from the edge on mobile and 24dp minimum on tablet/desktop.
   • FAB should change its color when it is focused.
   • A tool tip "Add users to group" should appear above FAB once it is focused.
   • FAB should always stay on the same place on desktop/mobile screen while page scrolling - near right bottom corner.
2. After FAB pressing popup window with search field and is displaying.
3. When administrator types in search field, the autocomplete list should be shown after the second typed symbol.
4. Search is performed by username and email which are displayed in autocomplete list.
5. Search should be performed both by local part and domain part of the email address.
6. Search is case-insensitive.
7. Max count of users in autocomplete list is 10.
8. Users in autocomplete list are sorted by username in alphabetical case-insensitive order.
9. If username or email that is being searched belongs to user that is already a member of usergroup, this user should not appear in autocomplete list.
10. When administrator clicks on user in autocomplete list, she is added to the top of the users in group table on page. Search input is cleaned, autocomplete list is cleared.

Known problems

Bug	link	Fixed
FAB tool tip is absent	link
Change user adding to group pop up UI and functionality	link
Open the autocomplete list after entering any character	link
Check field length error message is shown for 51 symbols entered	link
No blue highlighting for new user in group	link
The autocomplete list does not appear after the user data entry is started, if a space is entered before entering data	link
Error displaying FAB button on mobile device screens using the Web Developer Tool	link
Different place for FAB tooltip	link
After entering two characters and the list of autocomplete appears, users are sorted in the autocomplete list not in the order	link
Length error when entering two spaces in a row	link