Use StringUtilities.normalize to allow compilation with SBT 0.12.

Project.normalizeModuleID is recommended for use with SBT 0.13, but it
doesn't exist with 0.12. This uses the deprecated call instead.
Merge pull request #288 from garycoady/wip/docker-fix-normalized-name

Use StringUtilities.normalize to allow compilation with SBT 0.12.