Added ability to add/retrieve file assets to/from entities.

All updates revolve around adding and retrieving file assets.
Also added integration tests to test that this new code works correctly.
Updating travis.yml for possible bug in xctool
Updating Tests to separate unit and integration tests into different targets.
Also updating travis.yml to account for changes and to see if we can get integration tests working on their servers.
Removing Integration tests from travis.yml until issues can be resolved.
Updating integration tests for a workaround for xctool and travis-ci.
Disabling monitoring when running integration tests.
Updating travis.yml to make it run the tests with one command and parallelize them for faster execution.
Merge pull request #93 from RobertWalsh/master

Added ability to add/retrieve file assets to/from entities