Add schema to cursors

[tshemsedinov]

Here is an example of fetch callback arguments: err, data, cursor

{ err: null,
  data:
   [ { Name: 'Russian', Locale: 'ru' },
     { Name: 'Ukrainian', Locale: 'uk' } ],
  cursor:
   MemoryCursor {
     parent:
      MemoryCursor {
        parent: null,
        provider: null,
        dataset:
         [ { Name: 'English', Locale: 'en' },
           { Name: 'Ukrainian', Locale: 'uk' },
           { Name: 'Russian', Locale: 'ru' } ],
        children: [],
        jsql: [],
        schema:
         Dictionary {
           Name:
            { domain: 'Nomen', lookup: true, required: true, unique: true },
           Locale: { domain: 'Nomen', required: true, unique: true } },
        indices: {} },
     provider: null,
     dataset: undefined,
     children: [],
     jsql: [],
     schema:
      Dictionary {
        Name:
         { domain: 'Nomen', lookup: true, required: true, unique: true },
        Locale: { domain: 'Nomen', required: true, unique: true } },
     indices: {} } }

[tshemsedinov]

Landed in 6fd0962 and c84a8bb