Create new attributes for synchronization information about group

- create new module for existing attribute synchronizationEnabled,
  testing value (true, false or null)
- create new module for new attribute lastSynchronizationState, no check
  needed, only information about attribute
- create new module for new attribute lastSynchronizationTimestamp,
  check if timestamp is in correct format
- use new attributes in GroupSynchronizerThread in GroupsManagerBlImpl,
  method run, try to save information about synchronization of this
  group
- create new method saveInformationAboutGroupSynchronization in
  GroupsManagerBlImpl running in the new transaction (use in
  GroupSynchronizerThread)

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IMPORTANT: Need to do after merging this commit

1] create two new attributeDefinitions
 - urn_perun_group_attribute_def_def_lastSynchronizationState
 - urn_perun_group_attribute_def_def_lastSynchronizationTimestamp
2] set rights for these two attributeDefinitions
3] add these information to the changeLog
Documentation added and fixed

- javadoc fixes in AttributesManager and AttributesManagerBl
- documentation added and fixed in rpc, AttributesManagerMethod
Authz: VoObserver can call getVos
Merge pull request #420 from stavamichal/informationAboutGroupSynchronization

Create new attributes for synchronization information about group

- create new module for existing attribute synchronizationEnabled, testing value (true, false or null)
- create new module for new attribute lastSynchronizationState, no check needed, only information about attribute
- create new module for new attribute lastSynchronizationTimestamp, check if timestamp is in correct format
- use new attributes in GroupSynchronizerThread in GroupsManagerBlImpl, method run, try to save information about synchronization of this group
- create new method saveInformationAboutGroupSynchronization in GroupsManagerBlImpl running in the new transaction (use in GroupSynchronizerThread)
REGISTRAR: do not offer joining identities when user is known

- Backported and modified change from upstream/productionElixirFix.
  When checking for similar users, if user is known (by session or
  actor/extSource) we don't have to offer joining, since perun will
  join application on approval.

  Case when user is known by actor/extSource but not session is when
  user entry was created by previous application with auto-approval
  but session was not updated in GUI (linked app forms).

  Original version returned "no match" for any unknown user, which is not good.
  Check is not performed for non-authz users on GUI side, but this logic
  must be kept in registrar for users with federated identities which we can join
  and which might be found by name or email.
Documentation fix
parm fix in rpc

- removeAlsoUserFacilityAttributes changed to workWithUserAttributes
Documentation added and fixed
Merge pull request #434 from Simcsa/javadoc

Documentation added and fixed
REGISTRAR,GUI: Support for Heading and Timezone in app form

- Added new form item HEADING, which will be used as customizable
  heading of application form. Content is considered as HTML.

- HEADING is not saved with submitted application form.

- HTML_COMMENT and HEADING now have customized language pages
  on app form settings, since they only contain label and not
  error or help text.

- Added new form item TIMEZONE, which is pre-filled with
  existing timezones in GUI and user can manually select
  one or select "Not selected" option. When required, user
  must select one of timezones.
  Form item still must be manually linked to proper attribute,
  which is urn:perun:user:attribute-def:def:timezone.

- Fixed "onChange" behavior of all selection boxes on application
  form, since their validation was previously performed only on
  form submission. It's now performed on any selection change.
GUI: removed unused style for H1
Merge pull request #457 from zlamalp/style

GUI: removed unused style for H1
Merge pull request #456 from zlamalp/headerSupport

REGISTRAR,GUI: Support for Heading and Timezone in app form
Merge pull request #454 from zlamalp/backport

REGISTRAR: do not offer joining identities when user is known