Preparing old chain nodes

A proper version of ZEND and EON has been released to support the migration.
In particular:

• EON 1.5, with the following features:
  • Hardfork configured to stop backward transfers to the mainchain
  • Dump support via command-line
• ZEND 6, with the following features:
  • Hardfork configured to stop forward transfers to EON and sidechain creation
  • Stop of users transactions mining