Bump version to 2.0.0.0.
Bump version to 2.0.0.0.

We use 4 version components. The first 3 is the official versioning, while the last component is our unofficial versioning.

lxcid/google-toolbox-for-mac,lxcid/google-toolbox-for-mac,lxcid/google-toolbox-for-mac