GH-251 Fixed JDK 11 issues

- Added JDK 11 hook in FunctionCreatorConfiguration for javax.annotation to be loaded from current CL
- Ensured the file: protocol resources end with the forward slash. See UrlClassPath.getLoader of JDK 11 for more details as to why
- Re-enabled conditional  tests by removing Java 8 assumptions
- Part of the issue was also, the invoker plugin which was only generating ‘it/..’ directory every other time due to exists condition, thus resulting in some test failures every other time (missing directory)

Resolves #251

spring-cloud-function-deployer/pom.xml

@@ -17,8 +17,7 @@
 
 	<properties>
 		<wrapper.version>1.0.10.RELEASE</wrapper.version>
-		<spring.cloud.deployer.version>1.3.2.RELEASE</spring.cloud.deployer.version>
-		<skip.invoke>true</skip.invoke>
+		<spring.cloud.deployer.version>2.0.0.RELEASE</spring.cloud.deployer.version>
 	</properties>
 
 	<dependencies>
@@ -81,7 +80,6 @@
 				<version>3.0.1</version>
 				<configuration>
 					<localRepositoryPath>${project.build.directory}/local-repo</localRepositoryPath>
-					<skipInvocation>${skip.invoke}</skipInvocation>
 				</configuration>
 				<executions>
 					<execution>