Wire jump-to-entry into JabMap

[koppor]

Follow-up to palukku/jabref#9

(to make use of this endpoint)

[palukku]

The format for the selection command is:

POST http://localhost:23119/commands
Content-Type: application/json
Accept: application/json

{
  "commandId": "selectentries",
  "libraryId": "Chocolate.bib-670214c9",
  "citationKeys":[
    "Corti_2009",
    "Keen_2001"
  ],
  "entryIds":[
    "00000010"
  ]
}