Update travis to run japicmp in the main script and fix coveralls.

Anything that fails in after_success is ignored in travis reporting. The
checks must be done in the main script.

The japicmp was failing due to the lack of a jar to compare and so
coveralls was then not submitting. No coverage reports have been logged
by coveralls since June 2017.

.travis.yml

@@ -32,6 +32,9 @@ jdk:
 
 script:
   - mvn
+  # japicmp requires a package
+  - mvn jar:jar japicmp:cmp -P japicmp
 
 after_success:
-  - mvn clean test japicmp:cmp -P japicmp jacoco:report coveralls:report -Ptravis-jacoco
+  # jacoco will run in the main script. Include the profile to submit to coveralls.
+  - mvn jacoco:report coveralls:report -Ptravis-jacoco