Disable case sensitiveness for group names.
Notifications: constrains for notif objects added

- no two TemplateMessages with the same templateId and locale can exist
- no two Regexes with the same regular expression can exist
- no two Receivers with the same target and locale can exist
- created new PerunExceptions for each case in Notification module
GUI: handle aborted request (can't contact server)

- When request to server is aborted by browser (can't contact server), then
 status code of response is 0. Request must be handled in onResponseRecieved().

- Fixed display of connection lost widget in main GUI. Display it only
  when request is aborted by browser.
Merge pull request #565 from zlamalp/gui

GUI: handle aborted request (can't contact server)
UTILS: print also timestamp in pwdm log

- Also add help text for ldaps settings.
Change rules for getting rights for groupManager on attributes

 - change rules on member-resource attributes: only rights on any assigned
   group to resource are needed, add comment with definition of this rule
 - change rules on resource-group attributes: add comment with
   definition of this rule
 - change rules on user-facility attributes: groupManager need rights on
   any group (under resources of facility) which is from the same vo
   like some of users member, add comment with definition of this rule
 - change rules on user attributes: only has groupManager in vo where
   user has any member, add comment with definition of
   this rule
 - change rules on member attributes: only has groupManager in vo, where
   the member has membership, add comment with definition of this
   rule
 - change rules on vo attributes: change rights from NEVER to only
   has groupManager in vo, add comment with definition of this
 - do NOT change rules on group, resource, facility and host attributes
Merge pull request #566 from zlamalp/ldap

UTILS: print also timestamp in pwdm log
Merge pull request #562 from stavamichal/attributesRightsForGroupAdmin

Change rules for getting rights for groupManager on attributes
Fix and add some minor changes to XML extSource

 - xml extSource can send html header if it is set in configuration
 - fix closing of SSL connection
Merge pull request #567 from stavamichal/fixAndAddSomeMinorsToXMLExtSource

Fix and add some minor changes to XML extSource
remove limitation for testing machines from the master branch
SERVICES: Fixed ldap service for dc base

- When dc object is base of perun entries, we must add it
  at least one structural class (domain).

- When getting current ldap state, load also dc object using
  filter on objectclass=dcObject.
Merge pull request #569 from zlamalp/ldapservice

SERVICES: Fixed ldap service for dc base
GUI: unselect services in table after force propagation is started
Merge pull request #570 from zlamalp/gui

GUI: unselect services in table after force propagation is started
Notifications: skipping null values in messages

- new TemplateExceptionHandler created for skipping undefined values
  retrieving from java code
Merge pull request #568 from mvocu/engineNew-cleanup

remove limitation for testing machines from the master branch
Merge pull request #563 from jirmauritz/notification

Notifications: constrains for notif objects added and skipping null values of TemplateMessage
REGISTRAR: new version of tag replacements

- Registrar creates and uses new attribute holding base URL of Perun instance
  for VOs and groups. It's value is used in new tag replacements.

  If attribute is not set (for group) use VOs as backup.
  If attribute not set either (for VO) then use config property "perunUrl".

  If value can't be determined, replace tag by empty space.

- New tags look-like: {tagName-authz} or {tagName} when only attribute value
  is used. If authz is provided, it's appended after attribute value.
  Then, rest of address is calculated from provided context params.
GUI: use new tags in help for registrar notifications