Add option Default Group for Users in LDAP authentication UI.

When Default Group for Users is enabled in Configure - Configuration - Authentication,
this default group can be used for all ldap users who use LDAP for authentication only,
for example, when an LDAP server does not have memberof attribute for groups.

https://bugzilla.redhat.com/show_bug.cgi?id=1060207
Add test cases for User. authenticate_ldap.

https://bugzilla.redhat.com/show_bug.cgi?id=1060207
Support Default Group for Users with LDAP authentication.

When Default Group for Users is enabled in Configure - Configuration - Authentication,
this default group can be used for all ldap users who use LDAP for authentication only,
for example, when an LDAP server does not have memberof attribute for groups.

https://bugzilla.redhat.com/show_bug.cgi?id=1060207
Fixed show/hide of ldap_default_group_div & updated pull-down choices.

- Fixed show/hide of ldap_default_group_div
- Changed 'Default Group for Users' pull-down choice <Choose> to <No Default Group>

https://bugzilla.redhat.com/show_bug.cgi?id=1060207
Fix and cleanup miqButtons javascript.
Fix multiple miqButtons invocations.
Move left_cell_bottom level up to prevent duplicit DOM ids.
Fixed feature id passed to assert_privileges call.

- Fixed feature id passed to assert_privileges call.
- Added code to only build trees that logged in user has access to, after catalog was added/saved for a limited user, right_cell_replace was not finishing loading because it wasn't able to replace the tree partials that weren't even there.
- Added dictionary lookup in flash message call to show correct title in flash message when Catalog is added/edited.

https://bugzilla.redhat.com/show_bug.cgi?id=1159421
https://bugzilla.redhat.com/show_bug.cgi?id=1161271
Merge pull request #778 from lfu/default_group_for_ldap_users_1060207

Support Default Group for Users with LDAP authentication.
Updating an instance fails

Fixes #1082

This is related to the workaround put in for RAILS bug
https://github.com/rails/rails/issues/17466

The code was expecting all values to be present in the
ae_instance.ae_values, the import/export only add non-empty values.
The UI seems to add all values even if they are empty.
So in a new database after the import/export only non empty values are
present as soon as you save it in the DB all values get added by the UI.
If this is a issue we can open a separate git issue for it.
Merge pull request #1077 from martinpovolny/miq_buttons

miqButtons fixes
Avoid DOM id conflict by prefixing AE endpoint selection buttons.
Merge pull request #1081 from h-kataria/catalog_add_edit_fix

Fixed feature id passed to assert_privileges call.
Merge pull request #1078 from martinpovolny/automate_buttons

Automate endpoint miqButtons fix
Update CHANGELOG.md for Sprint 15

Add changes, removals, fixes, enhancements.
correct links to milestone Sprint 15 (the date end was changed)
Updated removed and changed sections per comments.
added UI bullet about I18N
Memoist gem bullet update

[skip ci]
Merge pull request #1035 from mfeifer/readme

Update CHANGELOG.md for Sprint 15
Merge pull request #1083 from mkanoor/git_issue_1082

Updating an instance fails
Add a few spec support modules for logger, paths, camcorder
Add a few recordings of disk images
Add a few specs using recorded disk images