Fixes to composer

- Terminated namespaces in the psr-0 definitions
- Added composer.lock and vendor/ to .gitignore
Fix failing unit tests

- Tests were not disabling original constructor of mocked object, leading to
  test errors. Moved all mock construction out of nested blocks to make more
  explicit, and modified to use getMockBuilder() to generate the mock objects.

- Added import statements

- Added file level docblock
CS and code review

- Added missing imports
- Ensured all class files had up-to-date license docblocks
- Added missing property and method docblocks
- Ensured typehints in docblocks were accurate
- Removed "swagger" generation artifacts
- Updated Controller to return a ContentNegotation ViewModel, not JsonModel,
  instance.
s/JsonSerializable/IteratorAggregate/

- Removed JsonSerializable implementation in favor of:
  - toArray() method, plus
  - IteratorAggregate implementation, that
  - returns an ArrayIterator with the return value of toArray()

This will work seamlessly with an ViewModel implementation.
CS fixes

- trailing whitespace
Fleshed out the README
Merge branch 'feature/code-review'

Completed code review of module to ensure it is ready for inclusion in the
package repositories. This included:

- CS review
- Docblock review
- Ensuring tests run consistently
- Ensuring composer is setup correctly, and that appropriate gitignore
  directives are in place
- Ensuring the provided ZF2 controller will properly handle content negotiation