Update travis to build crucible without -Werror.

.travis.yml

@@ -29,6 +29,8 @@ install:
 # Here starts the actual work to be performed for the package under test;
 # any command which exits with a non-zero exit code causes the build to fail.
 script:
+ # Build crucible with no -Werror
+ - stack build crucible
  # Build packages
  - stack build --ghc-options="-Wall -Werror"
  # Run tests