Switch from testem to karma, add coverage, clean up Gruntfile.

- Remove pkg from Gruntfile since it exists as package.
- Switch from testem to karma to support coverage.
- Adjust npm deps to refelct switch.
Update History.md
Merge branch 'release/0.8.0'
Merge tag '0.8.0' into develop

0.8.0
Start 0.9.0