Removed useless test repetition
Using Test::JSON to compare 2 JSONs

I was supprised, but I got this kind of error when the module was testes on
CPAN. The usage of Test::JSON should solve this problem.

http://www.cpantesters.org/cpan/report/c0e78a74-2337-11e3-b8b2-96b61dda783b

    #   Failed test 'StatusBoard::Graph basic usage'
    #   at t/001.t line 78.
    # +---+-------------------------------------+---+-------------------------------------+
    # | Ln|Got                                  | Ln|Expected                             |
    # +---+-------------------------------------+---+-------------------------------------+
    # |  2|   "graph" : {                       |  2|   "graph" : {                       |
    # |  3|      "datasequences" : [            |  3|      "datasequences" : [            |
    # |  4|         {                           |  4|         {                           |
    # |   |                                     *  5|            "title" : "X-Cola",      *
    # |  5|            "datapoints" : [         |  6|            "datapoints" : [         |
    # |  6|               {                     |  7|               {                     |
    # |  7|                  "value" : 22,      |  8|                  "value" : 22,      |
    # |  8|                  "title" : "2008"   |  9|                  "title" : "2008"   |
    # |  9|               },                    | 10|               },                    |
    # | 10|               {                     | 11|               {                     |
    # * 11|                  "value" : 24,      * 12|                  "title" : "2009",  *
    # * 12|                  "title" : "2009"   * 13|                  "value" : 24       *
    # | 13|               },                    | 14|               },                    |
    ...