RFR: vcs: handle binary files in UnifiedDiffParser

[Erik Helin]

Hi all,

please review this patch that handles binary files in the `UnifiedDiffParser`.

Testing:
- [x] Added a unit test
- [x] `make test` passes on Linux x64

Thanks,
Erik

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Commit messages:
 - vcs: handle binary files in UnifiedDiffParser

Changes: https://git.openjdk.java.net/skara/pull/930/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=930&range=00
  Stats: 17 lines in 2 files changed: 17 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/skara/pull/930.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/930/head:pull/930

PR: https://git.openjdk.java.net/skara/pull/930