Improve README.md, instructions and first use

[dexX7]

I'm a bit nitpicking here, but a few quick notes about the readme.

1. The / in the build example seems twisted:

-    .\gradlew bootRun
+    ./gradlew bootRun

2. The requirements should be stated, in particular that JDK 8 is required. It could be noted that JAVA_HOME must point to the correct version, when using ./gradlew. It might be noted that [a list of packages] is downloaded, which can be relevant for someone with a mobile data connection.

3. It would be great, if there were a few lines to what could be expected, when running ./gradlew bootRun. Before doing so I was wondering, how to use the project (i.e. I missed a "first use" example, and actually assumed the project focuses on a BitcoinJ RPC server), and then I was surprised for a moment, when I saw the rather wild messages of STOMP, until I noticed they are actually network messages. It was more obvious after the first transactions were listed.

It should be stated that bootRun connects to the P2P network.

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Other than that, this is really nice! :)

Edit: just found the other gems, like http://localhost:8080/listPeers (login: admin/admin).

[msgilligan]

I love your nitpicking @dexX7 -- it shows that you care!

[msgilligan]

Should be resolved in 71397fd. Closing. Let me know if I missed anything. Thanks!