EAD export: instances for archival_objects

This commit might beprobably sloppier than it should be. However,
for some reason the `ead_containers` method used in the top-level
<did> was not working for archival_objects. There's a slight change
in the tests that add some additional instances to the
archival_objects that get created.

TODO: Add more tests, esp. for DAOs that get exported from records
linked to archival_objects.
Merge pull request #5 from anarchivist/component-instance-export

Component instance export
EAD export: add new tests; simplify serializer code
Merge pull request #6 from anarchivist/ao-tests

EAD export: add new tests; simplify serializer code
Change RDE 'Add Children' to 'Save Rows'
Merge pull request #7 from anarchivist/rde-translation

Change RDE 'Add Children' to 'Save Rows'
Streamline build and Travis config

* Create new Travis-specific targets in the Ant build file:
`travis`, `travis:checkdb`, `travis:db:nuke`, and `travis:test`
	* Note: `travis:test` now runs **all** tests
* Ensure `db:nuke` gets run before each Selenium suite on MySQL
* Don't fetch Firefox or NodeJS by default
* Also, fix broken streaming spec
Merge pull request #8 from anarchivist/streamline-travis

Streamline Travis build