- Previously we had the Ceres version defined in two places, one in
  include/ceres/version.h, and one in the main CMakeLists.
- Now the main CMakeLists reads the Ceres version directly from
  version.h, as does the make_release script, so that we have a single
  place (version.h) in which the current Ceres version is defined.

Change-Id: Ie80aa7d38f5b576d3ed4d6109dd699f565c91027