erasure-code: HTML display of benchmark results

The ceph_erasure_code_benchmark output is converted into a JSON series
suitable to display in HTML with the http://www.flotcharts.org/
library. A self contained copy of the HTML,JS,CSS files is included for
durability and can be used from the source tree with:

  CEPH_ERASURE_CODE_BENCHMARK=src/ceph_erasure_code_benchmark  \
  PLUGIN_DIRECTORY=src/.libs \
      qa/workunits/erasure-code/bench.sh fplot jerasure |
      tee qa/workunits/erasure-code/bench.js

and display with:

  firefox qa/workunits/erasure-code/bench.html

Signed-off-by: Loic Dachary <loic@dachary.org>
COPYING: Cloudwatt copyright is inline

Remove partial list of contributions since Cloudwatt copyright has been
placed in the copyright notices of the files where works covered by
copyright have been included.

Signed-off-by: Loic Dachary <loic@dachary.org>