Added Poltergeist driver to Capybara for JS enabled tests

Use the Poltergeist driver for tests that require JavaScript
Updated the Vagrantfile to set RAM to 2GB w/2 virtual CPU's

The default VirtualBox configuration is 512MB w/1 virtual CPU.

I was running into insufficient memory problems but quadrupling the
memory and doubling the virtual CPU's should be sufficient without over
taxing low-horsepower contributors.
Added phantomjs installation to the provision of Vagrant instance
Moved the concerns and serializers back to normal locations. Not lib.
Merge pull request #235 from asm-helpful/621_missing_attachements

Code cleanup - put in PhantomJS/Poltergeist, moved Concerns and Serializers out of lib.