API

Fixes https://github.com/theodi/shared/issues/155

This returns JSON for validations, the recent validations and packages.

An example of validation JSON is as follows:

```JSON
{
  version: "0.1",
  licence: "http://opendatacommons.org/licenses/odbl/",
  validation: {
    url: "http://csvlint.dev/validation/5331771b537475e3aa1f0000",
    CSV: "https://extranet.who.int/tme/generateCSV.asp?ds=mdr_estimates",
    state: "valid",
    errors: [
      {
        type: "inconsistent_values",
        category: "schema",
        row: null,
        col: 27
      } 
    ],
    warnings: [ ],
    info: [ ],
    standardisedCSV: "http://csvlint.dev/validation/5331771b537475e3aa1f0000.csv",
    badges: {
      svg: "http://csvlint.dev/validation/5331771b537475e3aa1f0000.svg",
      png: "http://csvlint.dev/validation/5331771b537475e3aa1f0000.png"
    }
  }
}
```

List JSON is as follows:

```JSON
{
  version: "0.1",
  licence: "http://opendatacommons.org/licenses/odbl/",
  _links: {
    self: "http://csvlint.dev/validation?page=1",
    first: "http://csvlint.dev/validation?page=1",
    next: "http://csvlint.dev/validation?page=3",
    last: "http://csvlint.dev/validation?page=14"
  },
  validations: [
    {
    url: "http://csvlint.dev/validation/5332c85e537475e3a82c0000",
    CSV: "http://theodi.github.io/hot-drinks/hot-drinks.csv",
    state: "invalid"
    },
  ...
  ]
}
```

And package JSON is:

```JSON
{
  version: "0.1",
  licence: "http://opendatacommons.org/licenses/odbl/",
  package: {
    validations: [
      {
        url: "http://csvlint.dev/validation/532c2f565374751dbd000000",
        CSV: "http://dl.dropbox.com/u/16322775/extratofake.csv",
        state: "warnings"
      }
    ]
  }
}
```

Feedback is welcome!