scrooge: fix crossScalaVersion for scrooge-generator-tests

Problem / Solution

`scrooge-generator-tests` can't cross build for 2.12 yet, but
we'd still like to run the tests. This patch removes the
`scrooge-generator-tests` dependency for the `scrooge` project
definition and compiles the tests manually via our shell script.

RB_ID=846331

.travis.yml

@@ -29,9 +29,10 @@ before_script:
   - ./bin/travisci
   - travis_retry ./sbt ++$TRAVIS_SCALA_VERSION update
 
-script: 
+script:
   - travis_retry ./sbt ++$TRAVIS_SCALA_VERSION clean coverage test coverageReport
+  - travis_retry ./sbt ++$TRAVIS_SCALA_VERSION scrooge-generator-tests/coverage scrooge-generator-tests/test scrooge-generator-tests/coverageReport
   - ./sbt ++$TRAVIS_SCALA_VERSION coverageAggregate
 
-after_success: 
+after_success:
   - bash <(curl -s https://codecov.io/bash)

project/Build.scala

@@ -191,7 +191,7 @@ object Scrooge extends Build {
     base = file("."),
     settings = Defaults.coreDefaultSettings ++
       sharedSettings,
-    aggregate = publishedProjects :+ (scroogeGeneratorTests: sbt.ProjectReference)
+    aggregate = publishedProjects
   )
 
   // This target is used for publishing dependencies locally
@@ -254,7 +254,7 @@ object Scrooge extends Build {
     ),
     test in assembly := {},  // Skip tests when running assembly.
     publishArtifact := false
-  ).dependsOn(scroogeGenerator)
+  ).dependsOn(scroogeGenerator).settings(crossScalaVersions := Seq("2.11.8"))
 
   lazy val scroogeCore = Project(
     id = "scrooge-core",