enable build for jdk9

[brharrington]

Updates the travis config so that we build on
both jdk8 and jdk9.

[brharrington]

Travis build shows as success, but the tests failed on jdk9:

[info] Test com.netflix.iep.guice.GuiceClassFactoryTest.override started
[error] Test com.netflix.iep.guice.GuiceClassFactoryTest.override failed: java.lang.NoClassDefFoundError: javax/annotation/PostConstruct, took 0.027 sec
[error]     at com.netflix.iep.guice.AnnotationUtils.getPostConstruct(AnnotationUtils.java:38)
[error]     at com.netflix.iep.guice.AnnotationUtils.invokePostConstruct(AnnotationUtils.java:57)
[error]     at com.netflix.iep.guice.LifecycleModule$BindingListener.onProvision(LifecycleModule.java:42)
[error]     at com.google.inject.internal.ProvisionListenerStackCallback$Provision.provision(ProvisionListenerStackCallback.java:126)
[error]     at com.google.inject.internal.ProvisionListenerStackCallback.provision(ProvisionListenerStackCallback.java:68)
[error]     at com.google.inject.internal.MembersInjectorImpl$1.call(MembersInjectorImpl.java:86)
[error]     at com.google.inject.internal.MembersInjectorImpl$1.call(MembersInjectorImpl.java:80)
[error]     at com.google.inject.internal.InjectorImpl.callInContext(InjectorImpl.java:1085)
[error]     at com.google.inject.internal.MembersInjectorImpl.injectAndNotify(MembersInjectorImpl.java:80)
[error]     at com.google.inject.internal.Initializer$InjectableReference.get(Initializer.java:223)
[error]     at com.google.inject.internal.Initializer.injectAll(Initializer.java:132)
[error]     at com.google.inject.internal.InternalInjectorCreator.injectDynamically(InternalInjectorCreator.java:174)
[error]     at com.google.inject.internal.InternalInjectorCreator.build(InternalInjectorCreator.java:110)
[error]     at com.google.inject.Guice.createInjector(Guice.java:99)
[error]     at com.google.inject.Guice.createInjector(Guice.java:73)
[error]     at com.netflix.iep.guice.GuiceHelper.start(GuiceHelper.java:75)
[error]     at com.netflix.iep.guice.GuiceHelper.start(GuiceHelper.java:64)
[error]     at com.netflix.iep.guice.GuiceClassFactoryTest.override(GuiceClassFactoryTest.java:58)
[error]     at jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[error]     at jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[error]     at jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[error]     at java.lang.reflect.Method.invoke(Method.java:564)
...
[error] Failed: Total 5, Failed 1, Errors 0, Passed 4
[error] Failed tests:
[error] 	com.netflix.iep.admin.GuiceDebugEndpointTest
[error] (iep-module-admin/test:test) sbt.TestsFailedException: Tests unsuccessful
[error] (iep-guice/test:test) sbt.TestsFailedException: Tests unsuccessful
[error] Total time: 129 s, completed Aug 11, 2017, 9:57:17 PM

I suspect the problem is the tty hack added in #326.