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