Refactoring and fixes of /docker API endpoint.

This canges the output of the Docker endpoint to be a map so that it is
more consistent from single to multiple returns. It also refactors
internally how we handle both types of requests.

Without this PR the /docker API endpoint is broken completely so this
change in format has no effect anyways.

These changes are tested by the upcoming integration tests.
Merge pull request #316 from vmarmol/fixes

Refactoring and fixes of /docker API endpoint.
Adding integration test framework along with 3 tests.

These tests are similar to Go unit tests except that they're targetting
tesing of a running cAdvisor client. They do this by interacting with
the testing framework that is able to talk to the running cAdvisor. This
cAdvisor could be local or remote.
Fix raw driver's setting of CPU mask.

We used to include it with the trailing "\n" which gave us parsing
errors in the UI (and the reason why they didn't show up in any of those
containers).
Let the raw driver handle the /docker container.

This will give us stats on this container and since the /docker UI
endpoint, it no longer serves the purpose it once did.
Memory stats should not be omited if empty.

They may be zero. Also removed Limit from MemoryStats, that belongs in
MemorySpec and is there today. All info requests return the spec.
Add a case in the docs for the / bindmount error.

Fixes #303
Merge pull request #318 from vmarmol/fix-cpuset

Fix raw driver's setting of CPU mask.
Merge pull request #319 from vmarmol/omitempty-stats

Memory stats should not be omited if empty.
Merge pull request #321 from vmarmol/docs

Add a case in the docs for the / bindmount error.
Merge pull request #317 from vmarmol/integration

Adding integration test framework along with 3 tests.
Merge pull request #320 from vmarmol/docker-raw

Let the raw driver handle the /docker container.
Remove unused code.
Removing contributors file since it is always out of date and GitHub has a better record anyways.
Merge pull request #322 from vmarmol/cleanup

Misc cleanups