Add instructions how to build the samples

Provide more details how to build the code-samples in `README.md` or `readme.html`.

It's not obvious how to start with the code samples provided with Hazelcast. It's mainly important for people who didn't met Maven before.

The provided shell scripts don't build the sample themselves, they just expect the bits are ready in target directory.

**Interdependencies**
There is one more point related: it's not obvious if the samples are standalone or have some interdependecies. So if a user tries just one sample, it can experience dependency problems when another module (dependency) in not already in the local Maven repo.

Mention the possible cross-module dependenices in the readme too.