Embeddable link test now uses mocked HTTP server

The unit test for checking whether a page is embeddable in OAE now uses
a mocked HTTP server rather than apereo.org, to avoid any intermittent
test failures due to network connections, changes on their end, ..
Removed activity migration for 3.0.0 to 4.0.0
Merge pull request #838 from simong/838-embeddable-test

Intermittent test failure: previews embeddable check
Merge pull request #794 from simong/794-remove-activity-migration-code

Remove migration block in ActivityDAO
Merge pull request #821 from stuartf/external-restlib

use the external oae-rest module
Add swagger
add jsdoc
add tests for swagger
WIP swagger follow up
change swagger custom validation to use node-validator
populate resource models once at startup instead of on every request
simplify _addApiMethod logic
WIP swagger followup
Example new REST doc format
WIP use restjsdoc to populate swagger