Add CIS-CAT API requests

[mgmacias95]

Hello team,

This PR implements #87.

Some examples:

# curl -u foo:bar "localhost:55000/ciscat/001/results?pretty&benchmark=CIS+Ubuntu+Linux+16.04+LTS+Benchmark"
{
   "error": 0,
   "data": {
      "totalItems": 2,
      "items": [
         {
            "profile": "xccdf_org.cisecurity.benchmarks_profile_Level_2_-_Server",
            "scan": {
               "id": 474792628,
               "time": "2018-08-03T12:44:56.180-07:00"
            },
            "notchecked": 36,
            "pass": 104,
            "benchmark": "CIS Ubuntu Linux 16.04 LTS Benchmark",
            "unknown": 1,
            "score": 57,
            "error": 0,
            "fail": 79
         },
         {
            "profile": "xccdf_org.cisecurity.benchmarks_profile_Level_1_-_Workstation",
            "scan": {
               "id": 474792628,
               "time": "2018-08-03T12:45:29.037-07:00"
            },
            "notchecked": 71,
            "pass": 96,
            "benchmark": "CIS Ubuntu Linux 16.04 LTS Benchmark",
            "unknown": 0,
            "score": 64,
            "error": 0,
            "fail": 53
         }
      ]
   }
}
# curl -u foo:bar "localhost:55000/ciscat/001/results?pretty&benchmark=CIS+Ubuntu+Linux+16.04+LTS+Benchmark&offset=1"
{
   "error": 0,
   "data": {
      "totalItems": 2,
      "items": [
         {
            "profile": "xccdf_org.cisecurity.benchmarks_profile_Level_1_-_Workstation",
            "scan": {
               "id": 474792628,
               "time": "2018-08-03T12:45:29.037-07:00"
            },
            "notchecked": 71,
            "pass": 96,
            "benchmark": "CIS Ubuntu Linux 16.04 LTS Benchmark",
            "unknown": 0,
            "score": 64,
            "error": 0,
            "fail": 53
         }
      ]
   }
}
# curl -u foo:bar "localhost:55000/experimental/ciscat/results?pretty&profile=xccdf_org.cisecurity.benchmarks_profile_Level_1"
{
   "error": 0,
   "data": {
      "totalItems": 1,
      "items": [
         {
            "profile": "xccdf_org.cisecurity.benchmarks_profile_Level_1",
            "scan": {
               "id": 1873075658,
               "time": "2018-08-03T12:44:05.936-07:00"
            },
            "notchecked": 173,
            "pass": 78,
            "benchmark": "CIS Microsoft Windows 10 Enterprise Release 1607 Benchmark",
            "unknown": 3,
            "score": 26,
            "agent_id": "002",
            "error": 0,
            "fail": 224
         }
      ]
   }
}

Best regards,
Marta