Mostly-stylistic tweaks.

* tools/dist/release.py
  (Version.regex): Quote backslashes in a manner guaranteed to work.
  (Version.__str, Version.__str__): Unify these two identical methods
    under the latter, which is standard.  Callers updated.
  (Verify.__repr__): Use an equivalent but more pedantic way
    of constructing the return value.

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1485568 13f79535-47bb-0310-9956-ffa450edef68