Add testify/require to godeps
Refactoring Docker integration test.

Uses assert and require. Moves common components to a common file for
reuse.
Merge pull request #373 from vmarmol/release

cAdvisor 0.7.0.
Merge pull request #372 from vmarmol/integration3

Refactoring Docker integration test.
Add cpu frequency to machine info.
Merge pull request #375 from rjnagal/cpu

Add cpu frequency to machine info.
Check filesystem before accessing it in UI.

Fixes #377.