Extend index.json by additional file meta data.

# Changes in version 1.??.? - 2019-??-??

 * Medium changes

   - Extend index.json by including descriptor types, first and last

     publication timestamp, and SHA-256 file digest. Requires making

     configuration changes in collector.properties:

      1) IndexedPath is a new directory with subdirectories for

         archived and recent descriptors,

      2) ArchivePath and IndexPath are hard-wired to be subdirectories

         of IndexedPath,

      3) RecentPath must be set to be a subdirectory of IndexedPath,

      4) ContribPath has disappeared, and

      5) HtdocsPath is a new directory with files served by the web

         server.

# Changes in version 1.12.0 - 2019-10-18

  <property name="release.version" value="1.12.0-dev" />

  <property name="project-main-class" value="org.torproject.metrics.collector.Main" />

  <property name="name" value="collector"/>

  <property name="metricslibversion" value="2.8.0" />

  <property name="metricslibversion" value="2.9.0" />

  <property name="jarincludes" value="collector.properties logback.xml" />

  <patternset id="runtime" >

Subproject commit d82fff984634fe006ac7b0b102e7f48a52ca20d9

Subproject commit eb16cb359db41722e6089bafb1e26808df4338df

  RunOnce(Boolean.class),

  ExitlistUrl(URL.class),

  InstanceBaseUrl(String.class),

  ArchivePath(Path.class),

  ContribPath(Path.class),

  IndexedPath(Path.class),

  RecentPath(Path.class),

  OutputPath(Path.class),

  IndexPath(Path.class),

  StatsPath(Path.class),

  SyncPath(Path.class),

  HtdocsPath(Path.class),

  RelaySources(SourceType[].class),

  BridgeSources(SourceType[].class),

  BridgePoolAssignmentsSources(SourceType[].class),