Tweak 'svnadmin info' output: print each capability in its own line.

Before:
    % svnadmin info r | grep Capabilit
    Repository Capabilities: mergeinfo,foo
After:
    % svnadmin info r | grep Capabilit
    Repository Capability: mergeinfo
    Repository Capability: foo

* subversion/svnadmin/svnadmin.c
  (subcommand_info): As above.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1483856 13f79535-47bb-0310-9956-ffa450edef68