Enable Eclipse and Maven plugins on gradle

This pull request enables gradle tasks *install* (maven) and *eclipse*. The *install* task installs the evcache jars in the local Maven repository. The *eclipse* task creates a java eclipse project within "evcache-client" directory, allowing the project to be imported from eclipse.

In order to enable the maven *install* task, the version of the "servo:servo-core" dependency was specified as 0.4.44, otherwise the POM is not correctly generated.