Binary compatibility fixes for 2.0.1.

These are the remaining changes on top of 2.0-no-bin-compat to provide
binary compatibility with Slick 2.0.0. We also enable MiMa in the Travis
CI build to check this automatically for the 2.0 branch from now on.
Merge pull request #674 from slick/tmp/2.0.1-bin-compat

Binary compatibility fixes for 2.0.1.