Merge pull request #2812 from dotcloud/bump_v0.6.7

Bump v0.6.7
Bump version file to 0.7.0
Add 0.7.0 Changelog entry, with notable high-level features since 0.6.0.
Merge pull request #2857 from shykes/0.7-release

0.7 release
Merge branch 'release'