Support multiple versions of same libraries

[pun-ky]

Try to include guava with version 15 and 19 on instance
https://discuss.gradle.org/t/how-to-get-multiple-versions-of-the-same-library/7400/10
https://github.com/renatoathaydes/osgi-run/blob/master/osgi-run-core/src/main/groovy/com/athaydes/gradle/osgi/ConfigurationsCreator.groovy

Gradle by default prohibits it (most recent colliding version is taken), task is more related with https://github.com/neva-dev/gradle-osgi-plugin , but it is also here for clarification