[client][UsersView] Add tests for visibility of delete buttons

The tests will fail because I don't fix issue #686 yet.
[test][UsersView] Fix a variable name

     viewHTML ->
usersViewHTML
[test][UsersView] Clean up fixtures on finishing a test
[test][UsersView] Remove a needless function
[test][UsersView] Remove a needless argument of usersJson()
[test][UsersView] Fix a wrong parameter for respond()
[test][UsersView] Split tests to make clear purposes of each tests
[test][UsersView] Fix a duplicated user name in test data
[test][UsersView] Remove needless spaces
[test][UsersView] Extract generic code as a function
[test][ServersView] Add tests for visibility of delete button
[test][UsersView] Check existence of checkboxes for selecting delete items
[UsersView][HatoholMonitoringView] Fix visibility of delete button

The previous code has a bug that checkboxes for selecting delete
items aren't shown in spite of having a privilege.

github issue #686
[test][HatoholMonitoringView] Fix a broken test

The visibility of checkboxes for selecting delete items will be
managed by caller.
[test][ActionsView] Add tests for visibility of delete button
[test][ActionsView] Fix a wrong user object
[IncidentSettingsView] Enable to set visibility of delete buttons

This commit also add tests for it.
[test][ActionsView][ServersView][UsersView] Set default value of the argument of respond()
Merge pull request #691 from project-hatohol/issue-686-visibility-of-delete-button

Issue 686 visibility of delete button