Merge branch 'master' into stable-4.0

Merge branch 'master' into stable-4.0

* master:
  Silence non-externalized string warnings in org.eclipse.jgit
  Externalize translatable texts in org.eclipse.jgit
  Don't invalidate pack file on InterruptedIOException
  Update Mars target platforms to use Mars RC2 orbit
  Update build to use eclipse-jarsigner-plugin 1.1.2
  Guard agains null ReflogReader if named ref does not exist
  FS: Allow to manually set the path to the Git system config file
  FS: Fix a minor typo in runInShell() docs
  FS: Improve javadoc of some recently introduced methods
  Cleanup code and Eclipse compile errors in new gitrepo API
  Refactor to expose ManifestParser.
  FS: Remove the gitprefix logic
  SystemReader: Use discoverGitSystemConfig() in openSystemConfig()
  FS: Add a method to discover the system-wide config file
  FS: Extend readPipe() to optionally take additional environment
  FS: Document readpipe()'s encoding parameter
  Split discoverGitPrefix() code out into discoverGitExe()
  Equalize discoverGitPrefix() implementations between POSIX and Win32
  Move resolveGrandparentFile() to the base class for wider use
  Replace deprecated release() methods by close()
  Use AutoClosable to close resources in bundle org.eclipse.jgit
  ReceivePack: support quiet capability
  Fix ObjectReader resources leak

Change-Id: I0cd9f7ad57f26f0a0cbf412845d00ba1efbea346
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>