Update git submodules

* Update docs/submodules/appc.git from branch 'master'
  to 57293e84a0aa7405c9688448483d811d707e199a
  - Test coverage in MetricRegistryImpl
    
    Added test coverage for MetricRegistryImpl
    
    Issue-ID: APPC-1478
    Change-Id: I91eff5418ec14d294fa80af3d6d7025338b82072
    Signed-off-by: Joss Armstrong <joss.armstrong@ericsson.com>
    
1 file changed