Adds fact summary functionality to environment fact resolver

[bomoko]

This PR adds a a summary option to environment fact details.

Essentially, calling a query like the following

query allp {
  allProjects {
    name
    environments {
      name
      facts(summary:true) {
        id
        name
        source
        category
        description
      }
    }
  }
}

Will reduce duplicate facts -- where duplicates are considered those facts with identical names, values, and descriptions as being identical -- to single entries. source fields are, further, summarized into a single comma separated value. Unique fields such as id and created are made null, since in the context of summaries they make little sense.