Move mgmt submodule head

This also requires fixing paths to mgmt jars in build.mk
and usr.manifest as the version scheme has changed.

git log --format=short 7a4db4e759b..54f4810a7:

  commit 54f4810a76fabf955aeea34baefa336abf8b8467
  Author: Tomasz Grabiec <tgrabiec@cloudius-systems.com>

      Revert "supporting artifactory publish"

  commit 4abf771d146d6cde66f330e6b6ab6ececffb4cdd
  Author: Tomasz Grabiec <tgrabiec@cloudius-systems.com>

      mgmt/web: ditch jline-2.7 pulled by jruby-core

  commit 3863a3b58b661cd751314966cccb0f6c9835ed4a
  Author: Nadav Har'El <nyh@cloudius-systems.com>

      Moved RunJava to io.osv namespace

  commit be0717595f45d647062e7a41cc8dd38393c96547
  Author: Ronen Narkis <narkisr@gmail.com>

      supporting testing (jruby rake test does not work no matter what)

  commit 46e74f6bb886a0c62b06f08559fe2e44efdb8900
  Author: Ronen Narkis <narkisr@gmail.com>

      ignoring build

  commit 95ff3b70bae877d5d8cf0144853d1a201a0be333
  Author: Ronen Narkis <narkisr@gmail.com>

      verfying json existence and giving meaning full error

  commit 8b60c4a40aa4bcb7ce08bba600fd9cd6d63e1073
  Author: Ronen Narkis <narkisr@gmail.com>

      moving to three digit versioning in order to have a finer grained control on rel

  commit ffa7646388cec8d5b138ff4fc28a985c6344824c
  Author: Ronen Narkis <narkisr@gmail.com>

      supporting artifactory publish

  commit 8855112e2c867b4f855ed28ad9d9982c26bc56a3
  Author: Ronen Narkis <narkisr@gmail.com>

      clearing unused repo

  commit 3be79eb18b2be7bf1f28aaebd9905ac77945e4e4
  Author: Or Cohen <orc@fewbytes.com>

      Migrated ifconfig from previous JS console

  commit 287b014cf709e9c46692c59f87b70ebf056114b5
  Author: Or Cohen <orc@fewbytes.com>

      Migrated run command from previous CLI

  commit 0ffe064d30c1a812d7e853ee568ce45bfc16ed42
  Author: Or Cohen <orc@fewbytes.com>

      Added daemonizeIfNeeded helper method for commands

  commit 36951a86493c954a2e939648b5060260fac5b539
  Author: Or Cohen <orc@fewbytes.com>

      Moved ELFLoader from cloudius.cli to cloudius.util