Schema file additions

* Added AsteriskDialplan, AsteriskAccount and AsteriskMailbox  objectClasses
  to allow standalone dialplan, account and mailbox entries (STRUCTURAL)
* Added new Fields:
- AstAccountLanguage, AstAccountTransport, AstAccountPromiscRedir,
- AstAccountAccountCode, AstAccountSetVar, AstAccountAllowOverlap,
- AstAccountVideoSupport, AstAccountIgnoreSDPVersion
* Removed redundant IPaddr (there's already IPAddress)
- Gives more configuration Flags for SIP-Users available (tested)
- Allows to create Asterisk Attributes in defined Asterisk ObjectClasses
  without extensibleObject (which really should be the last resort); gives
  also additional possibilities for LDAP-filter 

(closes issue #15874)
Reported by: Medozas
Patches:
      asterisk.ldap-schema.patch uploaded by Medozas (license 41)
Tested by: Medozas, suretec


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@229050 65c4cc65-6c06-0410-ace0-fbb531ad65f3